Scanned antenna and method of inspecting scanned antenna

ABSTRACT

A scanning antenna includes a TFT substrate including a plurality of patch electrodes, a slot substrate including a slot electrode, and a liquid crystal layer provided between the TFT substrate and the slot substrate. The slot electrode includes a plurality of slots disposed corresponding to the plurality of patch electrodes and a solid portion not including the plurality of slot. When viewed from a normal direction of the substrate, the patch electrode is disposed across the slot in a first direction and overlaps the solid portion at both ends of the slot in each of a plurality of antenna units, and when viewed from the normal direction of the substrate, at least one of a periphery of the solid portion and a periphery of the patch electrode includes a recessed portion or a protruding portion in at least one antenna unit of the plurality of antenna units.

TECHNICAL FIELD

The disclosure relates to a scanning antenna and a method of inspecting a scanning antenna, and more particularly relates to a scanning antenna in which an antenna unit (also referred to as an “element antenna”) has a liquid crystal capacitance (also referred to as a “liquid crystal array antenna”) and a method of inspecting the scanning antenna.

BACKGROUND ART

Antennas for mobile communication and satellite broadcasting require functions that can change the beam direction (referred to as “beam scanning” or “beam steering”). As an example of an antenna (hereinafter referred to as a “scanning antenna”, and may be referred to as “scanned antenna”) having such functionality, phased array antennas equipped with antenna units are known. However, existing phased array antennas are expensive, which is an obstacle for popularization as a consumer product. In particular, as the number of antenna units increases, the cost rises considerably.

Therefore, scanning antennas that utilize the high dielectric anisotropy (birefringence) of liquid crystal materials (including nematic liquid crystals and polymer dispersed liquid crystals) have been proposed (PTL 1 to PTL 4 and NPL 1). Since the dielectric constant of liquid crystal materials has a frequency dispersion, in the present specification, the dielectric constant in a frequency band for microwaves (also referred to as the “dielectric constant for microwaves”) is particularly denoted as “dielectric constant M (ε_(M))”.

PTL 3 and NPL 1 describe how an inexpensive scanning antenna can be obtained by using liquid crystal display (hereinafter referred to as “LCD”) device technology.

CITATION LIST Patent Literature

-   PTL 1: JP 2007-116573 A -   PTL 2: JP 2007-295044 A -   PTL 3: JP 2009-538565 A -   PTL 4: JP 2013-539949 A

Non Patent Literature

-   NPL 1: R. A. Stevenson et al., “Rethinking Wireless Communications:     Advanced Antenna Design using LCD Technology”, SID 2015 DIGEST, pp.     827-830. -   NPL 2: M. ANDO et al., “A Radial Line Slot Antenna for 12 GHz     Satellite TV Reception”, IEEE Transactions of Antennas and     Propagation, Vol. AP-33, No. 12, pp. 1347-1353 (1985).

SUMMARY Technical Problem

As described above, although the idea of realizing an inexpensive scanning antenna by applying LCD technology is known, there are no documents that specifically describe the structure, manufacturing method, driving method, and inspection method of the scanning antennas using LCD technology.

Accordingly, an object of the disclosure is to provide a scanning antenna which can be mass-manufactured by utilizing the existing manufacturing techniques of LCDs and a method of inspecting a scanning antenna.

Solution to Problem

A scanning antenna according to an embodiment of the disclosure is a scanning antenna including a transmission and/or reception region including a plurality of antenna units arranged in the transmission and/or reception region and a non-transmission and/or reception region located in a region other than the transmission and/or reception region. The scanning antenna includes a thin film transistor (TFT) substrate including a first dielectric substrate, a plurality of TFTs supported by the first dielectric substrate, a plurality of gate bus lines, a plurality of source bus lines, and a plurality of patch electrodes, the plurality of TFTs and the plurality of patch electrodes being each disposed corresponding to the plurality of antenna units, a slot substrate including a second dielectric substrate and a slot electrode provided on a first main surface of the second dielectric substrate, a liquid crystal layer provided between the TFT substrate and the slot substrate, and a reflective conductive plate disposed opposing a second main surface of the second dielectric substrate, the second main surface being located on a side opposite to the first main surface, with a dielectric layer interposed between the reflective conductive plate and the second dielectric substrate. The slot electrode includes a plurality of slots disposed corresponding to the plurality of patch electrodes and a solid portion not including the plurality of slots, when viewed from a normal direction of the first dielectric substrate, in each of the plurality of antenna units, a patch electrode of the plurality of patch electrodes is disposed across a slot of the plurality of slots in a first direction and overlaps the solid portion at both ends of the slot, and when viewed from the normal direction of the first dielectric substrate, in at least one antenna unit of the plurality of antenna units, at least one of a periphery of the solid portion and a periphery of the patch electrode includes a recessed portion or a protruding portion.

In an embodiment, when viewed from the normal direction of the first dielectric substrate, in the at least one antenna unit, the recessed portion or the protruding portion includes a first recessed portion provided to the periphery of the solid portion, and the first recessed portion is located on a portion of the periphery of the solid portion overlapping the patch electrode.

In an embodiment, when viewed from the normal direction of the first dielectric substrate, in the at least one antenna unit, the recessed portion or the protruding portion includes a second recessed portion provided to the periphery of the patch electrode, and the second recessed portion is located on a portion of the periphery of the patch electrode overlapping the solid portion.

In an embodiment, when viewed from the normal direction of the first dielectric substrate, in the at least one antenna unit, the recessed portion or the protruding portion includes a first protruding portion provided to a portion of the periphery of the patch electrode extending in the first direction, and the first protruding portion is disposed with a width of the patch electrode in a second direction perpendicular to the first direction greater than a width of other portions on at least one end.

In an embodiment, when viewed from the normal direction of the first dielectric substrate, in the slot, the width of the patch electrode is greater at near the periphery of the solid portion than at other portions.

In an embodiment, the width of the patch electrode is greater at a portion overlapping the solid portion than at other portions.

A thickness of the patch electrode may be greater than or equal to 2 μm.

A thickness of the slot electrode may be greater than or equal to 2 μm.

In an embodiment, the recessed portion or the protruding portion is provided to only some antenna units of the plurality of antenna units.

A scanning antenna according to another embodiment of the disclosure is a scanning antenna including a transmission and/or reception region including a plurality of antenna units arranged in the transmission and/or reception region and a non-transmission and/or reception region located in a region other than the transmission and/or reception region. The scanning antenna includes a TFT substrate including a first dielectric substrate, a plurality of TFTs supported by the first dielectric substrate, a plurality of gate bus lines, a plurality of source bus lines, and a plurality of patch electrodes, the plurality of TFTs and the plurality of patch electrodes being disposed corresponding to the plurality of antenna units, a slot substrate including a second dielectric substrate and a slot electrode provided on a first main surface of the second dielectric substrate, a liquid crystal layer provided between the TFT substrate and the slot substrate, and a reflective conductive plate disposed opposing a second main surface of the second dielectric substrate, the second main surface being located on a side opposite to the first main surface, with a dielectric layer interposed between the reflective conductive plate and the second dielectric substrate. The slot electrode includes a plurality of slots disposed corresponding to the plurality of patch electrodes and a solid portion not including the plurality of slots, when viewed from a normal direction of the first dielectric substrate, in each of the plurality of antenna units, a patch electrode of the plurality of patch electrodes is disposed across a slot of the plurality of slots in a first direction and overlaps the solid portion at both ends of the slot, at least one antenna unit of the plurality of antenna units further includes a transparent electrode in contact with one electrode of the solid portion and the patch electrode and thinner than the one electrode, and when viewed from a normal direction of the first dielectric substrate, the transparent electrode does not overlap the one electrode and includes an alignment controlled region overlapping the other electrode with the liquid crystal layer interposed between the transparent electrode and the other electrode.

In an embodiment, the transparent electrode has an electric resistance greater than an electric resistance of the one electrode.

In an embodiment, the one electrode includes the solid portion, and the alignment controlled region is disposed while overlapping the patch electrodes in the slot.

In an embodiment, the one electrode includes the patch electrode.

In an embodiment, the alignment controlled region extends from a portion of a periphery of the patch electrode extending the first direction toward in a second direction perpendicular to the first direction.

In an embodiment, each of the TFT substrate and the slot substrate includes a transparent conductive layer which is the same transparent conductive layer for a terminal, and the transparent electrode is formed of a conductive film common to the transparent conductive layer of the TFT substrate or the slot substrate.

In an embodiment, the transparent electrode is formed of a semiconductor film common to an active layer of each of the plurality of TFTs.

A method for inspecting a scanning antenna according to an embodiment of the disclosure is a method for inspecting a scanning antenna including a transmission and/or reception region including a plurality of antenna units arranged in the transmission and/or reception region and a non-transmission and/or reception region located in a region other than the transmission and/or reception region, the scanning antenna including a TFT substrate including a first dielectric substrate, a plurality of TFTs supported by the first dielectric substrate, a plurality of gate bus lines, a plurality of source bus lines, and a plurality of patch electrodes, the plurality of TFTs and the plurality of patch electrodes being each disposed corresponding to the plurality of antenna units, a slot substrate including a second dielectric substrate and a slot electrode provided on a first main surface of the second dielectric substrate, a liquid crystal layer provided between the TFT substrate and the slot substrate, and a reflective conductive plate disposed opposing a second main surface of the second dielectric substrate, the second main surface being located on a side opposite to the first main surface, with a dielectric layer interposed between the reflective conductive plate and the second dielectric substrate, the slot electrode including a plurality of slots disposed corresponding to the plurality of patch electrodes and a solid portion not including the plurality of slots, each of the solid portion and a patch electrode of the plurality of patch electrodes being a metal electrode, and when viewed from a normal direction of the first dielectric substrate, in each of the plurality of antenna units, the patch electrode being disposed across a slot of the plurality of slots in a first direction and overlaps the solid portion at both ends of the slot, the method including a step (A) for selecting at least one antenna unit to be an inspection target from the plurality of antenna units, and a step (B) for observing a reflected light in a case that a visible light is incident on the at least one antenna unit that is selected from an upper side of the TFT substrate or the slot substrate, in a state that a predetermined voltage is applied to the slot electrode and a bus line connected the at least one antenna unit that is selected, of the plurality of source bus lines and the plurality of gate bus lines. In the step (B), assuming that, in the at least one antenna unit that is selected, one electrode of the solid portion and the patch electrode on an observing side is an upper electrode, and the other electrode is a lower electrode, when seen from an upper side of the upper electrode, a portion of a region that is not covered by the upper electrode and in which the lower electrode is present is an observation region at which the reflected light is observed, and the at least one antenna unit that is selected is determined for quality depending on a magnitude of an intensity of the reflected light from the observation region.

In an embodiment, the antenna unit to be the inspection target further includes a transparent electrode connected to the upper electrode, and in the step (B), the observation region includes a region where the transparent electrode overlaps the lower electrode with the liquid crystal layer interposed between the transparent electrode and the lower electrode, and the reflected light is observed through the transparent electrode.

In an embodiment, in the step (B), the observation region includes a region where a liquid crystal alignment can be changed in accordance with an oblique electric field generated between an edge of the upper electrode and the lower electrode.

In an embodiment, in the step (A), the plurality of antenna units are divided into a plurality of groups depending on the plurality of source bus lines or the plurality of gate bus lines connected to the plurality of antenna units, and at least one antenna unit to be the inspection target is selected in each of the plurality of groups.

In an embodiment, in a case where the at least one antenna unit that is selected is determined to have a failure, another antenna unit in the same group as the antenna unit determined to have a failure is subjected to the observation in the step (B).

Advantageous Effects of Disclosure

According to an embodiment of the disclosure, a scanning antenna which can be mass-manufactured by using the existing manufacturing technology of LCDs and a method of inspecting the scanning antenna are provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view schematically illustrating a portion of a scanning antenna 1000 according to a first embodiment.

FIG. 2A and FIG. 2B are schematic plan views illustrating a TFT substrate 101 and a slot substrate 201 in the scanning antenna 1000, respectively.

FIG. 3A and FIG. 3B are a cross-sectional view and a plane view schematically illustrating an antenna unit region U of the TFT substrate 101, respectively.

FIG. 4A to FIG. 4C are cross-sectional views schematically illustrating a gate terminal section GT, a source terminal section ST, and a transfer terminal section PT of the TFT substrate 101, respectively.

FIG. 5 is a diagram illustrating an example of a manufacturing process of the TFT substrate 101.

FIG. 6 is a cross-sectional view schematically illustrating an antenna unit region U and a terminal section IT in the slot substrate 201.

FIG. 7 is a schematic cross-sectional view for illustrating a transfer section in the TFT substrate 101 and the slot substrate 201.

FIG. 8A to FIG. 8C are cross-sectional views illustrating a gate terminal section GT, a source terminal section ST, and a transfer terminal section PT of a TFT substrate 102, respectively, in a second embodiment.

FIG. 9 is a diagram illustrating an example of a manufacturing process of the TFT substrate 102.

FIG. 10A to FIG. 10C are cross-sectional views illustrating a gate terminal section GT, a source terminal section ST, and a transfer terminal section PT of a TFT substrate 103, respectively, in a third embodiment.

FIG. 11 is a diagram illustrating an example of a manufacturing process of the TFT substrate 103.

FIG. 12 is a schematic cross-sectional view for illustrating a transfer section in the TFT substrate 103 and a slot substrate 203.

FIG. 13A is a schematic plan view of a TFT substrate 104 including a heater resistive film 68, and FIG. 13B is a schematic plan view for illustrating sizes of a slot 57 and a patch electrode 15.

FIG. 14A and FIG. 14B are diagrams illustrating a schematic structure and current distribution of resistance heating structures 80 a and 80 b, respectively.

FIG. 15A to FIG. 15C are diagrams illustrating a schematic structure and current distribution of resistance heating structures 80 c to 80 e, respectively.

FIG. 16A is a schematic cross-sectional view of a liquid crystal panel 100Pa including the heater resistive film 68, and FIG. 16B is a schematic cross-sectional view of a liquid crystal panel 100Pb including the heater resistive film 68.

FIG. 17 is a diagram illustrating an equivalent circuit of one antenna unit in a scanning antenna according to an embodiment of the disclosure.

FIG. 18A to FIG. 18C, and FIG. 18E to FIG. 18G are each a diagram illustrating an example of a waveform of each signal used for driving the scanning antenna according to an embodiment, and FIG. 18D is a diagram illustrating a waveform of a display signal of an LCD panel performing dot inversion driving.

FIG. 19A to FIG. 19E are each a diagram illustrating another example of a waveform of each signal used for driving the scanning antenna according to an embodiment.

FIG. 20A to FIG. 20E are each a diagram illustrating yet another example of waveforms of each signal used for driving the scanning antenna according to an embodiment.

FIG. 21A is a cross-sectional view schematically illustrating an alignment state of the antenna unit in the scanning antenna 1000, and FIG. 21B is a plan view exemplarily illustrating a result of observing an alignment state of each antenna unit from a side of the slot substrate 201.

FIG. 22A is a cross-sectional view schematically illustrating an alignment state of the antenna unit in the scanning antenna 1000, and FIG. 22B is a plan view exemplarily illustrating a result of observing an alignment state of each antenna unit from a side of the TFT substrate 101.

FIG. 23A and FIG. 23B are respectively a plan view and an enlarged plan view exemplarily illustrating an electrode shape of the present embodiment, and FIG. 23C is a plan view illustrating another example of the electrode shape.

FIGS. 24A and 24B are respectively a plan view and an enlarged plan view exemplarily illustrating another electrode shape of the present embodiment, and FIG. 24C is a plan view illustrating another example of the electrode shape.

FIG. 25A is a schematic cross-sectional view of a scanning antenna not including an inspection transparent electrode, and FIG. 25B is a schematic top view illustrating a result of observing a liquid crystal alignment of the antenna unit.

FIG. 26A and FIG. 26B are respectively a schematic cross-sectional view and a schematic top view of a scanning antenna 1000A provided with the inspection transparent electrodes, and FIG. 26C is a schematic top view illustrating a result of observing a liquid crystal alignment of an antenna unit.

FIG. 27 is a schematic cross-sectional view illustrating a modified example of the scanning antenna 1000A provided with the inspection transparent electrodes.

FIG. 28A and FIG. 28B are respectively a schematic cross-sectional view and a schematic top view illustrating another scanning antenna 1000B provided with the inspection transparent electrodes, and FIG. 28C is a top view illustrating an observation result of a liquid crystal alignment.

FIGS. 29A and 29B are respectively a schematic cross-sectional view and a schematic top view illustrating yet another scanning antenna 1000C provided with the inspection transparent electrodes, and FIG. 29C is a top view illustrating an observation result of a liquid crystal alignment.

FIGS. 30A to 30C are respectively schematic cross-sectional views and a schematic top view illustrating yet another scanning antenna 1000D provided with the inspection transparent electrodes, and FIG. 30D is a top view illustrating an observation result of a liquid crystal alignment.

FIG. 31 is a schematic cross-sectional view exemplarily illustrating the slot substrate 201 in which the inspection transparent electrode is disposed.

FIG. 32 is a schematic cross-sectional view exemplarily illustrating the TFT substrate 101 in which the inspection transparent electrode is disposed.

FIG. 33 is a schematic perspective view of an inspection device 401 used for alignment inspections I and II.

FIG. 34 is a schematic perspective view of another inspection device 402 used for the alignment inspections I and II.

FIG. 35A and FIG. 35B are a plan view exemplarily illustrating reference position marks of the scanning antenna 1000 and an enlarged top view of the mark, respectively.

FIG. 36 is a diagram illustrating an example of an inspection method of a liquid crystal alignment according to the present embodiment.

FIG. 37 is a diagram illustrating another example of the inspection method of the liquid crystal alignment according to the present embodiment.

FIG. 38 is a plan view illustrating a portion of the scanning antenna for illustrating an example of a method for selecting an antenna unit to be an inspection target.

FIG. 39 is a plan view illustrating a portion of the scanning antenna for illustrating another example of a method for selecting an antenna unit to be an inspection target.

FIG. 40A is a schematic diagram illustrating a structure of an existing LCD 900, and FIG. 40B is a schematic cross-sectional view of an LCD panel 900 a.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a scanning antenna and a manufacturing method thereof according to embodiments of the disclosure will be described with reference to the drawings. In the following description, first, the structure and manufacturing method of a known TFT-type LCD (hereinafter referred to as a “TFT-LCD”) will be described. However, the description of matters well-known within the technical field of LCDs may be omitted. For a description of basic TFT-LCD technology, please refer to, for example, Liquid Crystals, Applications and Uses, Vol. 1-3 (Editor: Birenda Bahadur, Publisher: World Scientific Pub Co Inc), or the like. For reference, the entire contents of the disclosures of the above documents are incorporated herein.

The structure and operation of a typical transmissive TFT-LCD (hereinafter simply referred to as an “LCD”) 900 will be described with reference to FIG. 40A and FIG. 40B. Here, an LCD 900 with a vertical electric field mode (for example, a TN mode or a vertical alignment mode) in which a voltage is applied in a thickness direction of a liquid crystal layer is provided as an example. The frame frequency (which is typically twice a polarity inversion frequency) of the voltage applied to the liquid crystal capacitance of the LCD is 240 Hz even at quad speed driving, and the dielectric constant C of the liquid crystal layer that serves as the dielectric layer of the liquid crystal capacitance of the LCD is different from the dielectric constant M (ε_(M)) of microwaves (for example, satellite broadcasting, the Ku band (from 12 to 18 GHz), the K band (from 18 to 26 GHz), and the Ka band (from 26 to 40 GHz)).

As is schematically illustrated in FIG. 40A, the transmissive LCD 900 includes a liquid crystal display panel 900 a, a control circuit CNTL, a backlight (not illustrated), and a power source circuit (not illustrated). The liquid crystal display panel 900 a includes a liquid crystal display cell LCC and a driving circuit including a gate driver GD and a source driver SD. The driving circuit may be, for example, mounted on a TFT substrate 910 of the liquid crystal display cell LCC, or all or a part of the driving circuit may be integrated (monolithic integration) with the TFT substrate 910.

FIG. 40B illustrates a schematic cross-sectional view of the liquid crystal display panel (hereinafter referred to as an “LCD panel”) 900 a included in the LCD 900. The LCD panel 900 a includes the TFT substrate 910, a counter substrate 920, and a liquid crystal layer 930 provided therebetween. Both the TFT substrate 910 and the counter substrate 920 include transparent substrates 911 and 921, such as glass substrates. In addition to glass substrates, plastic substrates may also be used as the transparent substrates 911 and 921 in some cases. The plastic substrates are formed of, for example, a transparent resin (for example, polyester) and a glass fiber (for example, nonwoven fabric).

A display region DR of the LCD panel 900 a is configured of pixels P arranged in a matrix. A frame region FR that does not serve as part of the display is formed around the display region DR. The liquid crystal material is sealed in the display region DR by a sealing portion (not illustrated) formed surrounding the display region DR. The sealing portion is formed by curing a sealing material including, for example, an ultraviolet curable resin and a spacer (for example, resin beads or silica beads), and bonds and secures the TFT substrate 910 and the counter substrate 920 to each other. The spacer in the sealing material controls a gap between the TFT substrate 910 and the counter substrate 920, that is, a thickness of the liquid crystal layer 930, to be constant. To suppress an in-plane variation in the thickness of the liquid crystal layer 930, columnar spacers are formed on light blocking portions (for example, on a wiring line) in the display region DR by using an ultraviolet curable resin. In recent years, as seen in LCD panels for liquid crystal televisions and smart phones, a width of the frame region FR that does not serve as part of the display is very narrow.

In the TFT substrate 910, a TFT 912, a gate bus line (scanning line) GL, a source bus line (display signal line) SL, a pixel electrode 914, an auxiliary capacitance electrode (not illustrated), and a CS bus line (auxiliary capacity line) (not illustrated) are formed on the transparent substrate 911. The CS bus line is provided parallel to the gate bus line. Alternatively, the gate bus line of the next stage may be used as the CS bus line (CS on-gate structure).

The pixel electrode 914 is covered with an alignment film (for example, a polyimide film) for controlling the alignment of the liquid crystals. The alignment film is provided so as to be in contact with the liquid crystal layer 930. The TFT substrate 910 is often disposed on the backlight side (the side opposite to the viewer).

The counter substrate 920 is often disposed on the observer side of the liquid crystal layer 930. The counter substrate 920 includes a color filter layer (not illustrated), a counter electrode 924, and an alignment film (not illustrated) on the transparent substrate 921. Since the counter electrode 924 is provided in common to a plurality of pixels P constituting the display region DR, it is also referred to as a common electrode. The color filter layer includes a color filter (for example, a red filter, a green filter, and a blue filter) provided for each pixel P, and a black matrix (light shielding layer) for blocking light unnecessary for display. The black matrix is arranged, for example, so as to block lights between the pixels P in the display region DR and at the frame region FR.

The pixel electrode 914 of the TFT substrate 910, the counter electrode 924 of the counter substrate 920, and the liquid crystal layer 930 therebetween constitute a liquid crystal capacitance Clc. Individual liquid crystal capacitances correspond to the pixels. To retain the voltage applied to the liquid crystal capacitance Clc (so as to increase what is known as the voltage retention rate), an auxiliary capacitance CS electrically connected in parallel with the liquid crystal capacitance Clc is formed. The auxiliary capacitance CS is typically composed of an electrode having the same potential as the pixel electrode 914, an inorganic insulating layer (for example, a gate insulating layer (SiO₂ layer)), and an auxiliary capacitance electrode connected to the CS bus line. Typically, the same common voltage as the counter electrode 924 is supplied from the CS bus line.

Factors responsible for lowering the voltage (effective voltage) applied to the liquid crystal capacitance Clc are (1) those based on a CR time constant which is a product of a capacitance value C_(Clc) of the liquid crystal capacitance Clc and a resistance value R, and (2) interfacial polarization due to ionic impurities included in the liquid crystal material and/or the orientation polarization of liquid crystal molecules. Among these, the contribution of the CR time constant of the liquid crystal capacitance Clc is large, and the CR time constant can be increased by providing an auxiliary capacitance CS electrically connected in parallel to the liquid crystal capacitance Clc. Note that a volume resistivity of the liquid crystal layer 930 that serves as the dielectric layer of the liquid crystal capacitance Clc exceeds the order of 10¹² Ω·cm in the case of widely used nematic liquid crystal materials.

A display signal supplied to the pixel electrode 914 is a display signal that is supplied to the source bus line SL connected to the TFT 912 when the TFT 912 selected by a scanning signal supplied from the gate driver GD to the gate bus line GL is turned on. Accordingly, the TFTs 912 connected to a particular gate bus line GL are simultaneously turned on, and at that time, corresponding display signals are supplied from the source bus lines SL connected to the respective TFTs 912 of the pixels P in that row. By performing this operation sequentially from the first row (for example, the uppermost row of a display surface) to the mth row (for example, the lowermost row of the display surface), one image (frame) is written in the display region DR composed of m rows of pixels and is displayed. Assuming that the pixels P are arranged in a matrix of m rows and n columns, at least n source bus lines SL are provided in total such that at least one source bus line SL corresponds to each pixel column.

Such scanning is referred to as line-sequential scanning, a time between one pixel row being selected and the next pixel row being selected is called a horizontal scan period, (1H), and a time between a particular row being selected and then being selected a second time is called a vertical scanning period, (1V), or a frame. Note that, in general, 1V (or 1 frame) is obtained by adding the blanking period to the period m·H for selecting all m pixel rows.

For example, when an input video signal is an NTSC signal, 1V (=1 frame) of an existing LCD panel is 1/60 of a second (16.7 milliseconds). The NTSC signals are interlaced signals, the frame frequency is 30 Hz, and the field frequency is 60 Hz, but in LCD panels, since it is necessary to supply display signals to all the pixels in each field, they are driven with 1V=( 1/60) second (driven at 60 Hz). Note that, in recent years, to improve the video display characteristics, there are LCD panels driven at double speed drive (120 Hz drive, 1V=( 1/120 second)), and some LCD panels are driven at quad speed (240 Hz drive, 1V=( 1/240 second)) for 3D displays.

When a DC voltage is applied to the crystal layer 930, the effective voltage decreases and the luminance of the pixel P decreases. Since the above-mentioned interface polarization and/or the orientation polarization contribute to the decrease in the effective voltage, it is difficult for the auxiliary capacitance CS to prevent the decrease in the effective voltage completely. For example, when a display signal corresponding to a particular intermediate gray scale is written into every pixel in every frame, the luminance fluctuates for each frame and is observed as flicker. In addition, when a DC voltage is applied to the liquid crystal layer 930 for an extended period of time, electrolysis of the liquid crystal material may occur. Furthermore, impurity ions segregate at one side of the electrode, so that the effective voltage may not be applied to the liquid crystal layer and the liquid crystal molecules may not move. To prevent this, the LCD panel 900 a is subjected to so-called AC driving. Typically, frame-reversal driving is performed in which the polarity of the display signal is inverted every frame (every vertical scanning period). For example, in existing LCD panels, the polarity inversion is performed every 1/60 second (a polarity inversion period is 30 Hz).

In addition, dot inversion driving, line reversal driving, or the like is performed in order to uniformly distribute the pixels having different polarities of applied voltages even within one frame. This is because it is difficult to completely match the magnitude of the effective voltage applied to the liquid crystal layer between a positive polarity and a negative polarity. For example, in a case where the volume resistivity of the liquid crystal material exceeds the order of 10¹² Ω·cm, flicker is hardly recognizable in a case where the dot inversion or line reversal driving is performed every 1/60 second.

With respect to the scanning signal and the display signal in the LCD panel 900 a, on the basis of the signals supplied from the control circuit CNTL to the gate driver GD and the source driver SD, the gate driver GD and the source driver SD supply the scanning signal and the display signal to the gate bus line GL and the source bus line SL, respectively. For example, the gate driver GD and the source driver SD are each connected to corresponding terminals provided on the TFT substrate 910. The gate driver GD and the source driver SD may be mounted on the frame region FR of the TFT substrate 910 as a driver IC, for example, or may be monolithically formed in the frame region FR of the TFT substrate 910.

The counter electrode 924 of the counter substrate 920 is electrically connected to a terminal (not illustrated) of the TFT substrate 910 with a conductive portion (not illustrated) known as a transfer therebetween. The transfer is formed, for example, so as to overlap with the sealing portion, or alternatively so as to impart conductivity to a part of the sealing portion. This is done to narrow the frame region FR. A common voltage is directly or indirectly supplied to the counter electrode 924 from the control circuit CNTL. Typically, the common voltage is also supplied to the CS bus line as described above.

Basic Structure of Scanning Antenna

By controlling the voltage applied to each liquid crystal layer of each antenna unit corresponding to the pixels of the LCD panel and changing the effective dielectric constant M (ε_(M)) of the liquid crystal layer for each antenna unit, a scanning antenna equipped with an antenna unit that uses the anisotropy (birefringence index) of a large dielectric constant M (ε_(M)) of a liquid crystal material forms a two-dimensional pattern by antenna units with different electrostatic capacitances (corresponding to displaying of an image by an LCD). An electromagnetic wave (for example, a microwave) emitted from an antenna or received by an antenna is given a phase difference depending on the electrostatic capacitance of each antenna unit, and gains a strong directivity in a particular direction depending on the two-dimensional pattern formed by the antenna units having different electrostatic capacitances (beam scanning). For example, an electromagnetic wave emitted from an antenna is obtained by integrating, with consideration for the phase difference provided by each antenna unit, spherical waves obtained as a result of input electromagnetic waves entering each antenna unit and being scattered by each antenna unit. It can be considered that each antenna unit functions as a “phase shifter”. For a description of the basic structure and operating principles of a scanning antenna that uses a liquid crystal material, refer to PTL 1 to PTL 4 as well as NPL 1 and NPL 2. NPL 2 discloses the basic structure of a scanning antenna in which spiral slots are arranged. For reference, the entire contents of the disclosures of PTL 1 to PTL 4 as well as NPL 1 and NPL 2 are incorporated herein.

Note that although the antenna units in the scanning antenna according to the embodiments of the disclosure are similar to the pixels of the LCD panel, the structure of the antenna units is different from the structure of the pixel of the LCD panel, and the arrangement of the plurality of antenna units is also different from the arrangement of the pixels in the LCD panel. A basic structure of the scanning antenna according to the embodiments of the disclosure will be described with reference to FIG. 1, which illustrates a scanning antenna 1000 of a first embodiment to be described in detail later. Although the scanning antenna 1000 is a radial in-line slot antenna in which slots are concentrically arranged, the scanning antennas according to the embodiments of the disclosure are not limited to this. For example, the arrangement of the slots may be any of various known arrangements.

FIG. 1 is a cross-sectional view schematically illustrating a portion of the scanning antenna 1000 of the present embodiment, and schematically illustrates a part of the cross-section along the radial direction from a power feed pin 72 (see FIG. 2B) provided near the center of the concentrically arranged slots.

The scanning antenna 1000 includes a TFT substrate 101, a slot substrate 201, a liquid crystal layer LC provided therebetween, and a reflective conductive plate 65 opposing the slot substrate 201 with an air layer 54 interposed between the slot substrate 201 and the reflective conductive plate 65. The scanning antenna 1000 transmits and receives microwaves from a side closer to the TFT substrate 101.

The TFT substrate 101 includes a dielectric substrate 1 such as a glass substrate, a plurality of patch electrodes 15, and a plurality of TFTs 10 formed on the dielectric substrate 1. Each patch electrode 15 is connected to a corresponding TFT 10. Each TFT 10 is connected to a gate bus line and a source bus line.

The slot substrate 201 includes a dielectric substrate 51 such as a glass substrate and a slot electrode 55 formed on a side of the dielectric substrate 51 closer to the liquid crystal layer LC. The slot electrode 55 includes a plurality of slots 57.

The reflective conductive plate 65 is disposed opposing the slot substrate 201 with the air layer 54 interposed between the reflective conductive plate 65 and the slot substrate 201. In place of the air layer 54, a layer formed of a dielectric (for example, a fluorine resin such as PTFE) having a small dielectric constant M for microwaves can be used. The slot electrode 55, the reflective conductive plate 65, and the dielectric substrate 51 and the air layer 54 therebetween function as a waveguide 301.

The patch electrode 15, the portion of the slot electrode 55 including the slot 57, and the liquid crystal layer LC therebetween constitute an antenna unit U. In each antenna unit U, one patch electrode 15 is opposed to a portion of the slot electrode 55 including one slot 57 with a liquid crystal layer LC interposed therebetween, thereby constituting the liquid crystal capacitance. The structure in which the patch electrode 15 and the slot electrode 55 oppose each other with the liquid crystal layer LC interposed therebetween is similar to the structure illustrated in FIGS. 40A and 40B in which the pixel electrode 914 and the counter electrode 924 of the LCD panel 900 a oppose each other with the liquid crystal layer 930 interposed therebetween. That is, the antenna unit U of the scanning antenna 1000 and the pixel P of the LCD panel 900 a have a similar configuration. In addition, the antenna unit has a configuration similar to the pixel P in the LCD panel 900 a in that the antenna unit has an auxiliary capacitance electrically connected in parallel with the liquid crystal capacitance (see FIG. 13A and FIG. 17). However, the scanning antenna 1000 has many differences from the LCD panel 900 a.

First, the performance required for the dielectric substrates 1 and 51 of the scanning antenna 1000 is different from the performance required for the substrate of the LCD panel.

Generally, transparent substrates that are transparent to visible light are used for LCD panels. For example, glass substrates or plastic substrates are used. In reflective LCD panels, since the substrate on the back side does not need transparency, a semiconductor substrate may be used in some cases. In contrast to this, it is preferable for the dielectric substrates 1 and 51 used for the antennas to have small dielectric losses with respect to microwaves (where the dielectric tangent with respect to microwaves is denoted as tan δ_(M)). The tan δ_(M) of each of the dielectric substrates 1 and 51 is preferably approximately less than or equal to 0.03, and more preferably less than or equal to 0.01. Specifically, a glass substrate or a plastic substrate can be used. Glass substrates are superior to plastic substrates with respect to dimensional stability and heat resistance, and are suitable for forming circuit elements such as TFTs, a wiring line, and electrodes using LCD technology. For example, in a case where the materials forming the waveguide are air and glass, as the dielectric loss of glass is greater, from the viewpoint that thinner glass can reduce the waveguide loss, it is preferable for the thickness to be less than or equal to 400 μm, and more preferably less than or equal to 300 μm. There is no particular lower limit, provided that the glass can be handled such that it does not break in the manufacturing process.

The conductive material used for the electrode is also different. In many cases, an ITO film is used as a transparent conductive film for pixel electrodes and counter electrodes of LCD panels. However, ITO has a large tan δ_(M) with respect to microwaves, and as such cannot be used as the conductive layer in an antenna. The slot electrode 55 functions as a wall for the waveguide 301 together with the reflective conductive plate 65. Accordingly, to suppress the transmission of microwaves in the wall of the waveguide 301, it is preferable that the thickness of the wall of the waveguide 301, that is, the thickness of the metal layer (Cu layer or Al layer) be large. It is known that in a case where the thickness of the metal layer is three times the skin depth, electromagnetic waves are attenuated to 1/20 (−26 dB), and in a case where the thickness is five times the skin depth, electromagnetic waves are attenuated to about 1/150 (−43 dB). Accordingly, in a case where the thickness of the metal layer is five times the skin depth, the transmittance of electromagnetic waves can be reduced to 1%. For example, for a microwave of 10 GHz, in a case where a Cu layer having a thickness of greater than or equal to 3.3 μm and an Al layer having a thickness of greater than or equal to 4.0 μm are used, microwaves can be reduced to 1/150. In addition, for a microwave of 30 GHz, in a case where a Cu layer having a thickness of greater than or equal to 1.9 μm and an Al layer having a thickness of greater than or equal to 2.3 μm are used, microwaves can be reduced to 1/150. In this way, the slot electrode 55 is preferably formed of a relatively thick Cu layer or Al layer. There is no particular upper limit for the thickness of the Cu layer or the Al layer, and the thicknesses can be set appropriately in consideration of the time and cost of film formation. The usage of a Cu layer provides the advantage of being thinner than the case of using an Al layer. Relatively thick Cu layers or Al layers can be formed not only by the thin film deposition method used in LCD manufacturing processes, but also by other methods such as bonding Cu foil or Al foil to the substrate. The thickness of the metal layer, for example, ranges from 2 μm to 30 μm. When the thin film deposition methods are used, the thickness of the metal layer is preferably less than or equal to 5 μm. Note that aluminum plates, copper plates, or the like having a thickness of several mm can be used as the reflective conductive plate 65, for example.

Since the patch electrode 15 does not configure the waveguide 301 like the slot electrode 55, a Cu layer or an Al layer can be used that have a smaller thickness than that of the slot electrode 55. However, the patch electrode 15 preferably has a low resistance in order to avoid loss resulting from the oscillation of free electrons near the slot 57 of the slot electrode 55 changing to heat when inducing oscillation of free electrons in the patch electrode 15. From the viewpoint of mass production, an Al layer is preferably used rather than a Cu layer, and the thickness of the Al layer is preferably from 0.5 μm to 2 μm, for example.

In addition, an arrangement pitch of the antenna units U is considerably different from that of a pixel pitch. For example, considering an antenna for microwaves of 12 GHz (Ku band), the wavelength λ is 25 mm, for example. Then, as described in PTL 4, since the pitch of the antenna unit U is less than or equal to λ/4 and/or less than or equal to λ/5, the arrangement pitch becomes less than or equal to 6.25 mm and/or less than or equal to 5 mm. This is ten times greater than the pixel pitch of the LCD panel. Accordingly, the length and width of the antenna unit U are also roughly ten times greater than the pixel length and width of the LCD panel.

Of course, the arrangement of the antenna units U may be different from the arrangement of the pixels in the LCD panel. Herein, although an example is illustrated in which the antenna units U are arranged in concentric circles (for example, refer to JP 2002-217640 A), the embodiment is not limited thereto, and the antenna units may be arranged in a spiral shape as described in NPL 2, for example. Furthermore, the antenna units may be arranged in a matrix as described in PTL 4.

The properties required for the liquid crystal material of the liquid crystal layer LC of the scanning antenna 1000 are different from the properties required for the liquid crystal material of the LCD panel. In the LCD panel, a change in a refractive index of the liquid crystal layer of the pixels allows a phase difference to be provided to the polarized visible light (wavelength of from 380 nm to 830 nm) such that the polarization state is changed (for example, the change in the refractive index allows the polarization axis direction of linearly polarized light to be rotated or the degree of circular polarization of circularly polarized light to be changed), whereby display is performed. In contrast, in the scanning antenna 1000 according to the embodiment, the phase of the microwave excited (re-radiated) from each patch electrode is changed by changing the electrostatic capacitance value of the liquid crystal capacitance of the antenna unit U. Accordingly, the liquid crystal layer preferably has a large anisotropy (Δε_(M)) of the dielectric constant M (ε_(M)) for microwaves, and tan δ_(M) is preferably small. For example, the Δε_(M) of greater than or equal to 4 and tan δ_(M) of less than or equal to 0.02 (values of 19 GHz in both cases) described in SID 2015 DIGEST pp. 824-826 written by M. Witteck et al, can be suitably used. In addition, it is possible to use a liquid crystal material having a Δε_(M) of greater than or equal to 0.4 and tan δ_(M) of less than or equal to 0.04 as described in POLYMERS 55 vol. August issue pp. 599-602 (2006), written by Kuki.

In general, the dielectric constant of a liquid crystal material has a frequency dispersion, but the dielectric anisotropy Δε_(M) for microwaves has a positive correlation with the refractive index anisotropy Δn with respect to visible light. Accordingly, it can be said that a material having a large refractive index anisotropy Δn with respect to visible light is preferable as a liquid crystal material for an antenna unit for microwaves. The refractive index anisotropy Δn of the liquid crystal material for LCDs is evaluated by the refractive index anisotropy for light having a wavelength of 550 nm. Here again, when a Δn (birefringence index) is used as an index for light having a wavelength of 550 nm, a nematic liquid crystal having a Δn of greater than or equal to 0.3, preferably greater than or equal to 0.4, can be used for an antenna unit for microwaves. Δn has no particular upper limit. However, since liquid crystal materials having a large Δn tend to have a strong polarity, there is a possibility that reliability may decrease. From the viewpoint of reliability, Δn is preferably less than or equal to 0.4. The thickness of the liquid crystal layer is, for example, from 1 μm to 500 μm.

Hereinafter, the structure and manufacturing method of the scanning antenna according to the embodiments of the disclosure will be described in more detail.

First Embodiment

First, a description is given with reference to FIG. 1 and FIGS. 2A and 2B. FIG. 1 is a schematic partial cross-sectional view of the scanning antenna 1000 near the center thereof as described above, and FIG. 2A and FIG. 2B are schematic plan views illustrating the TFT substrate 101 and the slot substrate 201 in the scanning antenna 1000, respectively.

The scanning antenna 1000 includes a plurality of antenna units U arranged two-dimensionally. In the scanning antenna 1000 exemplified here, the plurality of antenna units are arranged concentrically. In the following description, the region of the TFT substrate 101 and the region of the slot substrate 201 corresponding to the antenna unit U will be referred to as “antenna unit region”, and be denoted with the same reference numeral U as the antenna unit. In addition, as illustrated in FIG. 2A and FIG. 2B, in the TFT substrate 101 and the slot substrate 201, a region defined by the plurality of two-dimensionally arranged antenna unit regions is referred to as “transmission and/or reception region R1”, and a region other than the transmission and/or reception region R1 is called a “non-transmission and/or reception region R2”. A terminal section, a drive circuit, and the like are provided in the non-transmission and/or reception region R2.

FIG. 2A is a schematic plan view illustrating the TFT substrate 101 in the scanning antenna 1000.

In the illustrated example, the transmission and/or reception region R1 has a donut-shape when viewed from a normal direction of the TFT substrate 101. The non-transmission and/or reception region R2 includes a first non-transmission and/or reception region R2 a located at the center of the transmission and/or reception region R1 and a second non-transmission and/or reception region R2 b located at the periphery of the transmission and/or reception region R1. An outer diameter of the transmission and/or reception region R1, for example, is from 200 mm to 1500 mm, and is configured according to a data traffic volume or the like.

A plurality of gate bus lines GL and a plurality of source bus lines SL supported by the dielectric substrate 1 are provided in the transmission and/or reception region R1 of the TFT substrate 101, and the antenna unit regions U are defined by these wiring lines. The antenna unit regions U are, for example, arranged concentrically in the transmission and/or reception region R1. Each of the antenna unit regions U includes a TFT and a patch electrode electrically connected to the TFT. The source electrode of the TFT is electrically connected to the source bus line SL, and the gate electrode is electrically connected to the gate bus line GL. In addition, a drain electrode is electrically connected to the patch electrode.

In the non-transmission and/or reception region R2 (R2 a, R2 b), a seal region Rs is disposed surrounding the transmission and/or reception region R1. A sealing material (not illustrated) is applied to the seal region Rs. The sealing material bonds the TFT substrate 101 and the slot substrate 201 to each other, and also encloses liquid crystals between these substrates 101, 201.

A gate terminal section GT, the gate driver GD, a source terminal section ST, and the source driver SD are provided outside the sealing region Rs in the non-transmission and/or reception region R2. Each of the gate bus lines GL is connected to the gate driver GD with the gate terminal section GT therebetween. Each of the source bus lines SL is connected to the source driver SD with the source terminal section ST therebetween. Note that, in this example, although the source driver SD and the gate driver GD are formed on the dielectric substrate 1, one or both of these drivers may be provided on another dielectric substrate.

Also, a plurality of transfer terminal sections PT are provided in the non-transmission and/or reception region R2. The transfer terminal section PT is electrically connected to the slot electrode 55 (FIG. 2B) of the slot substrate 201. In the present specification, the connection section between the transfer terminal section PT and the slot electrode 55 is referred to as a “transfer section”. As illustrated in drawings, the transfer terminal section PT (transfer section) may be disposed in the seal region Rs. In this case, a resin containing conductive particles may be used as the sealing material. In this way, liquid crystals are sealed between the TFT substrate 101 and the slot substrate 201, and an electrical connection can be secured between the transfer terminal section PT and the slot electrode 55 of the slot substrate 201. In this example, although the transfer terminal section PT is disposed in both the first non-transmission and/or reception region R2 a and the second non-transmission and/or reception region R2 b, the transfer terminal section PT may be disposed in only one of them.

Note that the transfer terminal section PT (transfer section) need not be disposed in the seal region Rs. For example, the transfer terminal unit PT may be disposed outside the seal region Rs in the non-transmission and/or reception region R2.

FIG. 2B is a schematic plan view illustrating the slot substrate 201 in the scanning antenna 1000, and illustrates the surface of the slot substrate 201 closer to the liquid crystal layer LC.

In the slot substrate 201, the slot electrode 55 is formed on the dielectric substrate 51 extending across the transmission and/or reception region R1 and the non-transmission and/or reception region R2.

In the transmission and/or reception region R1 of the slot substrate 201, a plurality of slots 57 are formed in the slot electrode 55. The slot 57 is formed corresponding to the antenna unit region U on the TFT substrate 101. For the plurality of slots 57 in the illustrated example, a pair of slots 57 extending in directions substantially orthogonal to each other are concentrically disposed so that a radial inline slot antenna is configured. Since the scanning antenna 1000 includes slots that are substantially orthogonal to each other, the scanning antenna 1000 can transmit and receive circularly polarized waves.

A plurality of terminal sections IT of the slot electrode 55 are provided in the non-transmission and/or reception region R2. The terminal section IT is electrically connected to the transfer terminal section PT (FIG. 2A) of the TFT substrate 101. In this example, the terminal section IT is disposed within the seal region Rs, and is electrically connected to the corresponding transfer terminal section PT by a sealing material containing conductive particles.

In addition, the power feed pin 72 is disposed on a rear surface side of the slot substrate 201 in the first non-transmission and/or reception region R2 a. The power feed pin 72 allows microwaves to be inserted into the waveguide 301 constituted by the slot electrode 55, the reflective conductive plate 65, and the dielectric substrate 51. The power feed pin 72 is connected to a power feed device 70. Power feeding is performed from the center of the concentric circle in which the slots 57 are arranged. The power feed method may be either a direct coupling power feed method or an electromagnetic coupling method, and a known power feed structure can be utilized.

In the following, each component of the scanning antenna 1000 will be described in detail with reference to drawings.

Structure of TFT Substrate 101

Antenna Unit Region U

FIG. 3A and FIG. 3B are a cross-sectional view and a plane view schematically illustrating the antenna unit region U of the TFT substrate 101, respectively.

Each of the antenna unit regions U includes a dielectric substrate (not illustrated), a TFT 10 supported by the dielectric substrate, a first insulating layer 11 covering the TFT 10, a patch electrode 15 formed on the first insulating layer 11 and electrically connected to the TFT 10, and a second insulating layer 17 covering the patch electrode 15. The TFT 10 is disposed, for example, at or near an intersection of the gate bus line GL and the source bus line SL.

The TFT 10 includes a gate electrode 3, an island-shaped semiconductor layer 5, a gate insulating layer 4 disposed between the gate electrode 3 and the semiconductor layer 5, a source electrode 7S, and a drain electrode 7D. The structure of the TFT 10 is not particularly limited to a specific structure. In this example, the TFT 10 is a channel etch-type TFT having a bottom gate structure.

The gate electrode 3 is electrically connected to the gate bus line GL, and a scanning signal is supplied via the gate bus line GL. The source electrode 7S is electrically connected to the source bus line SL, and a data signal is supplied via the source bus line SL. The gate electrode 3 and the gate bus line GL may be formed of the same conductive film (gate conductive film). The source electrode 7S, the drain electrode 7D, and the source bus line SL may be formed from the same conductive film (source conductive film). The gate conductive film and the source conductive film are, for example, metal films. In the present specification, layers formed using a gate conductive film may be referred to as “gate metal layers”, and layers formed using a source conductive film may be referred to as “source metal layers”.

The semiconductor layer 5 is disposed overlapping with the gate electrode 3 with the gate insulating layer 4 interposed therebetween. In the illustrated example, a source contact layer 6S and a drain contact layer 6D are formed on the semiconductor layer 5. The source contact layer 6S and the drain contact layer 6D are disposed on both sides of a region where a channel is formed in the semiconductor layer 5 (channel region). The semiconductor layer 5 may be an intrinsic amorphous silicon (i-a-Si) layer, and the source contact layer 6S and the drain contact layer 6D may be n⁺ type amorphous silicon (n⁺-a-Si) layers.

The source electrode 7S is provided in contact with the source contact layer 6S and is connected to the semiconductor layer 5 with the source contact layer 6S interposed therebetween. The drain electrode 7D is provided in contact with the drain contact layer 6D and is connected to the semiconductor layer 5 with the drain contact layer 6D interposed therebetween.

The first insulating layer 11 includes a contact hole CH1 that at least reaches the drain electrode 7D of the TFT 10.

The patch electrode 15 is provided on the first insulating layer 11 and within the contact hole CH1, and is in contact with the drain electrode 7D in the contact hole CH1. The patch electrode 15 includes a metal layer. The patch electrode 15 may be a metal electrode formed only from a metal layer. The material of the patch electrode 15 may be the same as that of the source electrode 7S and the drain electrode 7D. However, a thickness of the metal layer in the patch electrode 15 (a thickness of the patch electrode 15 when the patch electrode 15 is a metal electrode) is set to be greater than thicknesses of the source electrode 7S and the drain electrode 7D. The thickness of the metal layer in the patch electrode 15 in the case of being formed using an Al layer is set to, for example, greater than or equal to 0.5 μm.

A CS bus line CL may be provided using the same conductive film as that of the gate bus line GL. The CS bus line CL may be disposed overlapping with the drain electrode (or extended portion of the drain electrode) 7D with the gate insulating layer 4 interposed therebetween, and may constitute the auxiliary capacity CS having the gate insulating layer 4 as a dielectric layer.

An alignment mark (for example, a metal layer) 21 and a base insulating film 2 covering the alignment mark 21 may be formed at a position closer to the dielectric substrate than a position of the gate bus line GL. The alignment mark 21 is used as follows. When manufacturing m TFT substrates from one glass substrate, in a case where the number of photomasks is n (where n<m), for example, it is necessary to perform each exposure process multiple times. In this way, when the number (n) of photomasks is less than the number (m) of TFT substrates 101 manufactured from one glass substrate 1, the alignment mark 21 can be used for alignment of the photomasks. The alignment marks 21 may be omitted.

In the present embodiment, the patch electrode 15 is formed on a layer different from the source metal layer. This provides the advantages described below.

Since the source metal layer is typically formed using a metal film, it is conceivable to form a patch electrode in the source metal layer (as in the TFT substrate of the reference example). However, the patch electrode preferably has a low resistance such that the electron oscillation is not inhibited, and is formed of, for example, an Al layer having a relatively thick thickness of 0.5 μm or greater. For this reason, in the TFT substrate of the reference example, the source bus line SL and the like are also formed from a thick metal film, and problems arise where the controllability of the patterning reduces when wiring lines are formed. In contrast, in the present embodiment, since the patch electrode 15 is formed separately from the source metal layer, the thickness of the source metal layer and the thickness of the patch electrode 15 can be controlled independently. This allows the controllability for forming the source metal layer to be secured and a patch electrode 15 having a desired thickness to be formed.

In the present embodiment, the thickness of the patch electrode 15 can be set with a high degree of freedom separately from the thickness of the source metal layer. Note that since the size of the patch electrode 15 need not be controlled as strictly as the source bus line SL or the like, it is acceptable for the line width shift (deviation from the design value) to be increased by thickening the patch electrode 15. A case that the thickness of the patch electrode 15 is equal to the thickness of the source metal layer is not excluded.

The patch electrode 15 may include a Cu layer or an Al layer as a main layer. A performance of the scanning antenna correlates with an electric resistance of the patch electrode 15, and a thickness of the main layer is set so as to obtain a desired resistance. In terms of the electric resistance, there is a possibility that the thickness of the patch electrode 15 can be made thinner in the Cu layer than in the Al layer.

Gate Terminal Section GT, Source Terminal Section ST, and Transfer Terminal Section PT

FIG. 4A to FIG. 4C are cross-sectional views schematically illustrating the gate terminal section GT, the source terminal section ST, and the transfer terminal section PT, respectively.

The gate terminal section GT includes the gate bus line GL formed on the dielectric substrate, an insulating layer covering the gate bus line GL, and a gate terminal upper connection section 19 g. The gate terminal upper connection section 19 g is in contact with the gate bus line GL within a contact hole CH2 formed in the insulating layer. In this example, the insulating layer covering the gate bus line GL includes the gate insulating layer 4, the first insulating layer 11 and the second insulating layer 17 in that order from the dielectric substrate side. The gate terminal upper connection section 19 g is, for example, a transparent electrode formed of a transparent conductive film provided on the second insulating layer 17.

The source terminal section ST includes the source bus line SL formed on the dielectric substrate (here, on the gate insulating layer 4), an insulating layer covering the source bus line SL, and a source terminal upper connection section 19 s. The source terminal upper connection section 19 s is in contact with the source bus line SL within a contact hole CH3 formed in the insulating layer. In this example, the insulating layer covering the source bus line SL includes the first insulating layer 11 and the second insulating layer 17. The source terminal upper connection section 19 s is, for example, a transparent electrode formed of a transparent conductive film provided on the second insulating layer 17.

The transfer terminal section PT include a patch connection section 15 p formed on the first insulating layer 11, the second insulating layer 17 covering the patch connection section 15 p, and a transfer terminal upper connection section 19 p. The transfer terminal upper connection section 19 p is in contact with the patch connection section 15 p within a contact hole CH4 formed in the second insulating layer 17. The patch connection section 15 p is formed of the same conductive film as that of the patch electrode 15. The transfer terminal upper connection section (also referred to as an upper transparent electrode) 19 p is, for example, a transparent electrode formed of a transparent conductive film provided on the second insulating layer 17. In the present embodiment, the upper connection sections 19 g, 19 s, and 19 p for the respective terminal sections are formed of the same transparent conductive film.

In the present embodiment, it is advantageous that the contact holes CH2, CH3, and CH4 of the respective terminal sections can be simultaneously formed by the etching process after the formation of the second insulating layer 17. The detailed manufacturing process thereof will be described later.

Manufacturing Method of TFT Substrate 101

As an example, the TFT substrate 101 can be manufactured by the following method. FIG. 5 is a diagram exemplifying the manufacturing process of the TFT substrate 101.

First, a metal film (for example, a Ti film) is formed on a dielectric substrate and patterned to form the alignment mark 21. A glass substrate, a plastic substrate (resin substrate) having heat resistance, or the like can be used as the dielectric substrate, for example. Next, the base insulating film 2 is formed so as to cover the alignment marks 21. An SiO₂ film is used as the base insulating film 2.

Subsequently, a gate metal layer including the gate electrode 3 and the gate bus line GL is formed on the base insulating film 2.

The gate electrode 3 can be formed integrally with the gate bus line GL. Here, a not-illustrated gate conductive film (with a thickness of greater than or equal to 50 nm and less than or equal to 500 nm) is formed on the dielectric substrate by a sputtering method or the like. Next, the gate conductive film is patterned to obtain the gate electrode 3 and the gate bus line GL. The material of the gate conductive film is not particularly limited to a specific material. A film containing a metal such as aluminum (Al), tungsten (W), molybdenum (Mo), tantalum (Ta), chromium (Cr), titanium (Ti), or copper (Cu), an alloy thereof, or alternatively a metal nitride thereof can be appropriately used. Here, as a gate conductive film, a layered film is formed by layering MoN (having a thickness of 50 nm, for example), Al (having a thickness of 200 nm, for example), and MoN (having a thickness of 50 nm, for example) in this order.

Next, the gate insulating layer 4 is formed so as to cover the gate metal layer. The gate insulating layer 4 can be formed by a CVD method or the like. As the gate insulating layer 4, a silicon oxide (SiO₂) layer, a silicon nitride (SiNx) layer, a silicon oxynitride (SiOxNy; x>y) layer, a silicon nitride oxide (SiNxOy; x>y) layer, or the like may be used as appropriate. The gate insulating layer 4 may have a layered structure. Here, a SiNx layer (having a thickness of 410 nm, for example) is formed as the gate insulating layer 4.

Next, the semiconductor layer 5 and a contact layer are formed on the gate insulating layer 4. Here, an intrinsic amorphous silicon film (with a thickness of 125 nm, for example) and an n⁺ type amorphous silicon film (with a thickness of 65 nm, for example) are formed in this order and patterned to obtain an island-shaped semiconductor layer 5 and a contact layer. The semiconductor film used for the semiconductor layer 5 is not limited to an amorphous silicon film. For example, an oxide semiconductor layer may be formed as the semiconductor layer 5. In this case, it is not necessary to provide a contact layer between the semiconductor layer 5 and the source/drain electrodes.

Next, a source conductive film (having a thickness of greater than or equal to 50 nm and less than or equal to 500 nm, for example) is formed on the gate insulating layer 4 and the contact layer, and patterned to form a source metal layer including the source electrode 7S, the drain electrode 7D, and the source bus line SL. At this time, the contact layer is also etched, and the source contact layer 6S and the drain contact layer 6D separated from each other are formed.

The material of the source conductive film is not particularly limited to a specific material. A film containing a metal such as aluminum (Al), tungsten (W), molybdenum (Mo), tantalum (Ta), chromium (Cr), titanium (Ti), or copper (Cu), an alloy thereof, or alternatively a metal nitride thereof can be appropriately used. Here, as a source conductive film, a layered film is formed by layering MoN (having a thickness of 30 nm, for example), Al (having a thickness of 200 nm, for example), and MoN (having a thickness of 50 nm, for example) in this order. Instead, as a source conductive film, a layered film may be formed by layering Ti (having a thickness of 30 nm, for example), MoN (having a thickness of 30 nm, for example), Al (having a thickness of 200 nm, for example), and MoN (having a thickness of 50 nm, for example) in this order.

Here, for example, a source conductive film is formed by a sputtering method and the source conductive film is patterned by wet etching (source/drain separation). Thereafter, a portion of the contact layer located on the region that will serve as the channel region of the semiconductor layer 5 is removed by dry etching, for example, to form a gap portion, and the source contact layer 6S and the drain contact layer 6D are separated. At this time, in the gap portion, the area around the surface of the semiconductor layer 5 is also etched (overetching).

Note that, when a layered film in which a Ti film and an Al film are layered in this order is used as a source conductive film, for example, after patterning the Al film by wet etching using, for example, an aqueous solution of phosphoric acid, acetic acid, and nitric acid, the Ti film and the contact layer (n⁺ type amorphous silicon layer) 6 may be simultaneously patterned by dry etching. Alternatively, it is also possible to collectively etch the source conductive film and the contact layer. However, in the case of simultaneously etching the source conductive film or the lower layer thereof and the contact layer 6, it may be difficult to control the distribution of the etching amount of the semiconductor layer 5 (the amount of excavation of the gap portion) of the entire substrate. In contrast, as described above, in a case where etching is performed in an etching step separate from the formation of the source/drain separation and the gap portion formation, the etching amount of the gap portion can be more easily controlled.

Next, the first insulating layer 11 is formed so as to cover the TFT 10. In this example, the first insulating layer 11 is disposed so as to be in contact with the channel region of the semiconductor layer 5. In addition, the contact hole CH1 that at least reaches the drain electrode 7D is formed in the first insulating layer 11 by a known photolithographic method.

The first insulating layer 11 may be an inorganic insulating layer such as a silicon oxide (SiO₂) film, a silicon nitride (SiNx) film, a silicon oxynitride (SiOxNy; x>y) film, or a silicon nitride oxide (SiNxOy; x>y) film, for example. Here, as the first insulating layer 11, a SiNx layer having a thickness of 330 nm, for example, is formed by a CVD method.

Next, a patch conductive film is formed on the first insulating layer 11 and within the contact hole CH1, and this is subsequently patterned. In this way, the patch electrode 15 is formed in the transmission and/or reception region R1, and the patch connection section 15 p is formed in the non-transmission and/or reception region R2. The patch electrode 15 is in contact with the drain electrode 7D within the contact hole CH1. Note that, in the present specification, the layer including the patch electrode 15 and the patch connection section 15 p formed from the patch conductive film may be referred to as a “patch metal layer” in some cases.

The same material as that of the gate conductive film or the source conductive film can be used as the material of the patch conductive film. However, the patch conductive film is set to be thicker than the gate conductive film and the source conductive film. This allows the transmittance of electromagnetic waves to be kept low and the sheet resistance of the patch electrode to reduce. And thus, the loss resulting from the oscillation of free electrons in the patch electrode changing to heat can be reduced. A suitable thickness of the patch conductive film is, for example, greater than or equal to 1 μm and less than or equal to 30 μm. In a case where the thickness of the patch conductive film becomes thinner than this, the transmittance of the electromagnetic waves becomes roughly 30%, the sheet resistance becomes greater than or equal to 0.03 Ω/sq, and there is a possibility of the loss becoming larger, and conversely in a case where the thickness of the patch conductive film is thick, there is a possibility of the patterning characteristics of the slot deteriorating.

Here, as a patch conductive film, a layered film (MoN/Al/MoN) is formed by layering MoN (having a thickness of 50 nm, for example), Al (having a thickness of 1000 nm, for example), and MoN (having a thickness of 50 nm, for example) in this order. Instead, a layered film (MoN/Al/MoN/Ti) may be formed by layering Ti (having a thickness of 50 nm, for example), MoN (having a thickness of 50 nm, for example), Al (having a thickness of 2000 nm, for example), and MoN (having a thickness of 50 nm, for example) in this order. Alternatively, instead, a layered film (MoN/Al/MoN/Ti) may be formed by layering Ti (having a thickness of 50 nm, for example), MoN (having a thickness of 50 nm, for example), Al (having a thickness of 500 nm, for example), and MoN (having a thickness of 50 nm, for example) in this order. Alternatively, a layered film (Ti/Cu/Ti) in which a Ti film, a Cu film, and a Ti film are layered in this order, or a layered film (Cu/Ti) in which a Ti film and a Cu film are layered in this order may be used.

Next, the second insulating layer (having a thickness of greater than or equal to 100 nm and less than or equal to 300 nm) 17 is formed on the patch electrode 15 and the first insulating layer 11. The second insulating layer 17 is not particularly limited to a specific film, and, for example, a silicon oxide (SiO₂) film, a silicon nitride (SiNx) film, a silicon oxynitride (SiOxNy; x>y) film, a silicon nitride oxide (SiNxOy; x>y) film, or the like can be used as appropriate. Here, as the second insulating layer 17, for example, a SiNx layer having a thickness of 200 nm is formed.

Thereafter, the inorganic insulating films (the second insulating layer 17, the first insulating layer 11, and the gate insulating layer 4) are etched collectively by dry etching using a fluorine-based gas, for example. During the etching, the patch electrode 15, the source bus line SL, and the gate bus line GL each function as an etch stop. In this way, the contact hole CH2 that at least reaches the gate bus line GL is formed in the second insulating layer 17, the first insulating layer 11, and the gate insulating layer 4, and the contact hole CH3 that at least reaches the source bus line SL is formed in the second insulating layer 17 and the first insulating layer 11. In addition, the contact hole CH4 that at least reaches the patch connection section 15 p is formed in the second insulating layer 17.

In this example, since the inorganic insulating films are etched collectively, side surfaces of the second insulating layer 17, first insulating layer 11, and gate insulating layer 4 are aligned on a side wall of the obtained contact hole CH2, and the side walls of the second insulating layer 17 and first insulating layer 11 are aligned on a side wall of the contact hole CH3. Note that, in the present embodiment, the expression that “the side surfaces of different two or more layers are aligned” within the contact hole does not only refer to when the side surfaces exposed in the contact hole in these layers are flush in the vertical direction, but also includes cases where inclined surfaces such as continuous tapered shapes are formed. Such a structure can be obtained, for example, by etching these layers using the same mask, or alternatively by using one of these layers as a mask to etch the other layer.

Next, a transparent conductive film (having a thickness of greater than or equal to 50 nm and less than or equal to 200 nm) is formed on the second insulating layer 17 and within the contact holes CH2, CH3, and CH4 by a sputtering method, for example. An indium tin oxide (ITO) film, an IZO film, a zinc oxide (ZnO) film or the like can be used as the transparent conductive film. Here, an ITO film having a thickness of, for example, 100 nm is used as the transparent conductive film.

Next, the transparent conductive film is patterned to form the gate terminal upper connection section 19 g, the source terminal upper connection section 19 s, and the transfer terminal upper connection section 19 p. The gate terminal upper connection section 19 g, the source terminal upper connection section 19 s, and the transfer terminal upper connection section 19 p are used for protecting the electrodes or wiring lines exposed at each terminal section. In this way, the gate terminal section GT, the source terminal section ST, and the transfer terminal section PT are obtained.

Structure of Slot Substrate 201

Next, the structure of the slot substrate 201 will be described in greater detail.

FIG. 6 is a cross-sectional view schematically illustrating the antenna unit region U and the terminal section IT in the slot substrate 201.

The slot substrate 201 includes the dielectric substrate 51 having a front surface and a rear surface, a third insulating layer 52 formed on the front surface of the dielectric substrate 51, the slot electrode 55 formed on the third insulating layer 52, and a fourth insulating layer 58 covering the slot electrode 55. A reflective conductive plate 65 is disposed opposing the rear surface of the dielectric substrate 51 with the dielectric layer (air layer) 54 interposed therebetween. The slot electrode 55 and the reflective conductive plate 65 function as walls of the waveguide 301.

In the transmission and/or reception region R1, a plurality of slots 57 are formed in the slot electrode 55. The slot 57 is an opening that opens through the slot electrode 55. In this example, one slot 57 is disposed in each antenna unit region U.

The fourth insulating layer 58 is formed on the slot electrode 55 and within the slot 57. The material of the fourth insulating layer 58 may be the same as the material of the third insulating layer 52. By covering the slot electrode 55 with the fourth insulating layer 58, the slot electrode 55 and the liquid crystal layer LC are not in direct contact with each other, so that the reliability can be enhanced. In a case where the slot electrode 55 is formed of a Cu layer, Cu may elute into the liquid crystal layer LC in some cases. In addition, in a case where the slot electrode 55 is formed of an Al layer by using a thin film deposition technique, the Al layer may include a void. The fourth insulating layer 58 can prevent the liquid crystal material from entering the void of the Al layer. Note that in a case where the slot electrode 55 is formed by bonding an aluminum foil as the Al layer on the dielectric substrate 51 with an adhesive and patterning it, the problem of voids can be avoided.

The slot electrode 55 includes a main layer 55M such as a Cu layer or an Al layer. The slot electrode 55 may have a layered structure that includes the main layer 55M, as well as an upper layer 55U and a lower layer 55L disposed sandwiching the main layer 55M therebetween. A thickness of the main layer 55M may be set in consideration of the skin effect depending on the material, and may be, for example, greater than or equal to 2 μm and less than or equal to 30 μm. The thickness of the main layer 55M is typically greater than the thickness of the upper layer 55U and the lower layer 55L.

In the illustrated example, the main layer 55M is a Cu layer, and the upper layer 55U and the lower layer 55L are Ti layers. By disposing the lower layer 55L between the main layer 55M and the third insulating layer 52, the adhesion between the slot electrode 55 and the third insulating layer 52 can be improved. In addition, by providing the upper layer 55U, corrosion of the main layer 55M (e.g., the Cu layer) can be suppressed.

Since the reflective conductive plate 65 constitutes the wall of the waveguide 301, it is desirable that the reflective conductive plate 65 has a thickness that is three times or greater than the skin depth, and preferably five times or greater. An aluminum plate, a copper plate, or the like having a thickness of several millimeters manufactured by a cutting out process can be used as the reflective conductive plate 65.

The terminal section IT is provided in the non-transmission and/or reception region R2. The terminal section IT includes the slot electrode 55, the fourth insulating layer 58 covering the slot electrode 55, and an upper connection section 60. The fourth insulating layer 58 includes an opening that at least reaches the slot electrode 55. The upper connection section 60 is in contact with the slot electrode 55 within the opening. In the present embodiment, the terminal section IT is disposed in the seal region Rs, and is connected to the transfer terminal section on the TFT substrate (transfer section) by a seal resin containing conductive particles.

Transfer Section

FIG. 7 is a schematic cross-sectional view for illustrating the transfer section connecting the transfer terminal section PT of the TFT substrate 101 and the terminal section IT of the slot substrate 201. In FIG. 7, the same reference numerals are attached to the same components as those in FIG. 1 to FIG. 4C.

In the transfer section, the upper connection section 60 of the terminal section IT is electrically connected to the transfer terminal upper connection section 19 p of the transfer terminal section PT in the TFT substrate 101. In the present embodiment, the upper connection section 60 and the transfer terminal upper connection section 19 p are connected with a resin (sealing resin) 73 (also referred to as a sealing portion 73) including conductive beads 71 therebetween.

Each of the upper connection sections 60 and 19 p is a transparent conductive layer such as an ITO film or an IZO film, and there is a possibility that an oxide film is formed on the surface thereof. When an oxide film is formed, the electrical connection between the transparent conductive layers cannot be ensured, and the contact resistance may increase. In contrast, in the present embodiment, since these transparent conductive layers are bonded with a resin including conductive beads (for example, Au beads) 71 therebetween, even in a case where a surface oxide film is formed, the conductive beads pierce (penetrate) the surface oxide film, allowing an increase in contact resistance to be suppressed. The conductive beads 71 may penetrate not only the surface oxide film but also penetrate the upper connection sections 60 and 19 p which are the transparent conductive layers, and directly contact the patch connection section 15 p and the slot electrode 55.

The transfer section may be disposed at both a center portion and a peripheral portion (that is, inside and outside of the donut-shaped transmission and/or reception region R1 when viewed from the normal direction of the scanning antenna 1000) of the scanning antenna 1000, or alternatively may be disposed at only one of them. The transfer section may be disposed in the seal region Rs in which the liquid crystals are sealed, or may be disposed outside the seal region Rs (opposite to the liquid crystal layer).

Manufacturing Method of Slot Substrate 201

The slot substrate 201 can be manufactured by the following method, for example.

First, the third insulating layer (having a thickness of 200 nm, for example) 52 is formed on the dielectric substrate. A substrate such as a glass substrate or a resin substrate having a high transmittance to electromagnetic waves (the dielectric constant CM and the dielectric loss tan δ_(M) are small) can be used as the dielectric substrate. The dielectric substrate is preferably thin in order to suppress the attenuation of the electromagnetic waves. For example, after forming the constituent elements such as the slot electrode 55 on the front surface of the glass substrate by a process to be described later, the glass substrate may be thinned from the rear side. This allows the thickness of the glass substrate to be reduced to 500 μm or less, for example.

When a resin substrate is used as the dielectric substrate, constituent elements such as TFTs may be formed directly on the resin substrate, or may be formed on the resin substrate by a transfer method. In a case of the transfer method, for example, a resin film (for example, a polyimide film) is formed on the glass substrate, and after the constituent elements are formed on the resin film by the process to be described later, the resin film on which the constituent elements are formed is separated from the glass substrate. Generally, the dielectric constant CM and the dielectric loss tan δ_(M) of resin are smaller than those of glass. The thickness of the resin substrate is, for example, from 3 μm to 300 μm. Besides polyimide, for example, a liquid crystal polymer can also be used as the resin material.

The third insulating layer 52 is not particularly limited to a specific film, and, for example, a silicon oxide (SiO₂) film, a silicon nitride (SiNx) film, a silicon oxynitride (SiOxNy; x>y) film, a silicon nitride oxide (SiNxOy; x>y) film, or the like can be used as appropriate.

Next, a metal film is formed on the third insulating layer 52, and this is patterned to obtain the slot electrode 55 including the plurality of slots 57. As the metal film, a Cu film (or Al film) having a thickness of from 2 μm to 5 μm may be used. Here, a layered film obtained by layering a Ti film, a Cu film, and a Ti film in this order is used. Instead, a layered film may be formed by layering Ti (having a thickness of 50 nm, for example) and Cu (having a thickness of 5000 nm, for example) in this order.

Thereafter, the fourth insulating layer (having a thickness of 100 nm or 200 nm, for example) 58 is formed on the slot electrode 55 and within the slot 57. The material of the fourth insulating layer 58 may be the same as the material of the third insulating layer. Subsequently, in the non-transmission and/or reception region R2, an opening that at least reaches the slot electrode 55 is formed in the fourth insulating layer 58.

Next, a transparent conductive film is formed on the fourth insulating layer 58 and within the opening of the fourth insulating layer 58, and is patterned to form the upper connection section 60 in contact with the slot electrode 55 within the opening. In this way, the terminal section IT is obtained.

Material and Structure of TFT 10

In the present embodiment, a TFT including a semiconductor layer 5 as an active layer is used as a switching element disposed in each pixel. The semiconductor layer 5 is not limited to an amorphous silicon layer, and may be a polysilicon layer or an oxide semiconductor layer.

In a case where an oxide semiconductor layer is used, the oxide semiconductor included in the oxide semiconductor layer may be an amorphous oxide semiconductor or a crystalline oxide semiconductor including a crystalline portion. Examples of the crystalline oxide semiconductor include a polycrystalline oxide semiconductor, a microcrystalline oxide semiconductor, or a crystalline oxide semiconductor having a c-axis oriented substantially perpendicular to the layer surface.

The oxide semiconductor layer may have a layered structure of two or more layers. In cases where the oxide semiconductor layer has a layered structure, the oxide semiconductor layer may include an amorphous oxide semiconductor layer and a crystalline oxide semiconductor layer. Alternatively, the oxide semiconductor layer may include a plurality of crystalline oxide semiconductor layers having different crystal structures. In addition, the oxide semiconductor layer may include a plurality of amorphous oxide semiconductor layers. In cases where the oxide semiconductor layer has a two-layer structure including an upper layer and a lower layer, an energy gap of the oxide semiconductor included in the upper layer is preferably greater than an energy gap of the oxide semiconductor included in the lower layer. However, when the different in the energy gap between these layers is relatively small, the energy gap of the lower layer oxide semiconductor may be larger than the energy gap of the upper layer oxide semiconductor.

JP 2014-007399 A, for example, describes materials, structures, film formation methods, and the configuration of oxide semiconductor layers having layered structures for amorphous oxide semiconductors and each of the above described crystalline oxide semiconductors. For reference, the entire contents of JP 2014-007399 A are incorporated herein.

The oxide semiconductor layer may include, for example, at least one metal element selected from In, Ga, and Zn. In the present embodiment, the oxide semiconductor layer includes, for example, an In—Ga—Zn—O based semiconductor (for example, indium gallium zinc oxide). Here, the In—Ga—Zn—O based semiconductor is a ternary oxide of In (indium), Ga (gallium), and Zn (zinc), and the ratio (composition ratio) of In, Ga, and Zn is not particularly limited to a specific value. For example, the ratio includes In:Ga:Zn=2:2:1, In:Ga:Zn=1:1:1, or In:Ga:Zn=1:1:2. Such an oxide semiconductor layer can be formed from an oxide semiconductor film including an In—Ga—Zn—O based semiconductor. Note that channel etch type TFTs with an active layer including an oxide semiconductor, such as In—Ga—Zn—O based semiconductors, may be referred to as a “CE-OS-TFT” in some cases.

The In—Ga—Zn—O based semiconductor may be an amorphous semiconductor or a crystalline semiconductor. A crystalline In—Ga—Zn—O based semiconductor in which the c-axis is oriented substantially perpendicular to the layer surface is preferable as the crystalline In—Ga—Zn—O based semiconductor.

Note that the crystal structure of the crystalline In—Ga—Zn—O based semiconductor is disclosed in, for example, the above-mentioned JP 2014-007399 A, JP 2012-134475 A, and JP 2014-209727 A. For reference, the entire contents of JP 2012-134475 A and 2014-209727 A are incorporated herein. Since a TFT including an In—Ga—Zn—O based semiconductor layer has high mobility (more than 20 times in comparison with a-Si TFTs) and low leakage current (less than 1/100th in comparison with a-Si TFTs), such a TFT can suitably be used as a driving TFT (for example, a TFT included in a drive circuit provided in the non-transmission and/or reception region) and a TFT provided in each antenna unit region.

In place of the In—Ga—Zn—O based semiconductor, the oxide semiconductor layer may include another oxide semiconductor. For example, the oxide semiconductor layer may include an In—Sn—Zn—O based semiconductor (for example, In₂O₃—SnO₂—ZnO; InSnZnO). The In—Sn—Zn—O based semiconductor is a ternary oxide of In (indium), Sn (tin), and Zn (zinc). Alternatively, the oxide semiconductor layer may include an In—Al—Zn—O based semiconductor, an In—Al—Sn—Zn—O based semiconductor, a Zn—O based semiconductor, an In—Zn—O based semiconductor, a Zn—Ti—O based semiconductor, a Cd—Ge—O based semiconductor, a Cd—Pb—O based semiconductor, CdO (cadmium oxide), a Mg—Zn—O based semiconductor, an In—Ga—Sn—O based semiconductor, an In—Ga—O based semiconductor, a Zr—In—Zn—O based semiconductor, an Hf—In—Zn—O based semiconductor, an Al—Ga—Zn—O based semiconductor, or a Ga—Zn—O based semiconductor.

In the example illustrated in FIG. 3A and FIG. 3B, the TFT 10 is a channel etch type TFT having a bottom gate structure. The channel etch type TFT does not include an etch stop layer formed on the channel region, and a lower face of an end portion of each of the source and drain electrodes, which is closer to the channel, is provided so as to be in contact with an upper face of the semiconductor layer. The channel etch type TFT is formed by, for example, forming a conductive film for a source/drain electrode on a semiconductor layer and performing source/drain separation. In the source/drain separation process, the surface portion of the channel region may be etched.

Note that the TFT 10 may be an etch stop type TFT in which an etch stop layer is formed on the channel region. In the etch stop type TFT, the lower face of an end portion of each of the source and drain electrodes, which is closer to the channel, is located, for example, on the etch stop layer. The etch stop type TFT is formed as follows; after forming an etch stop layer covering the portion that will become the channel region in a semiconductor layer, for example, a conductive film for the source and drain electrodes is formed on the semiconductor layer and the etch stop layer, and source/drain separation is performed.

In addition, although the TFT 10 has a top contact structure in which the source and drain electrodes are in contact with the upper face of the semiconductor layer, the source and drain electrodes may be disposed to be in contact with the lower face of the semiconductor layer (a bottom contact structure). Furthermore, the TFT 10 may have a bottom gate structure having a gate electrode on the dielectric substrate side of the semiconductor layer, or a top gate structure having a gate electrode above the semiconductor layer.

Second Embodiment

The scanning antenna of a second embodiment will be described with reference to drawings. The TFT substrate of the scanning antenna of the present embodiment differs from the TFT substrate 101 illustrated in FIG. 2A in that a transparent conductive layer that serves as an upper connection section for each terminal section is provided between the first insulating layer and the second insulating layer of the TFT substrate.

FIG. 8A to FIG. 8C are cross-sectional views illustrating the gate terminal section GT, the source terminal section ST, and the transfer terminal section PT, respectively, of a TFT substrate 102 in the present embodiment. Constituent elements similar to those in FIG. 4A to FIG. 4C are denoted by the same reference numerals, and the description thereof is omitted. Since the cross-sectional structure of the antenna unit region U is similar to that of the above-described embodiments (FIG. 3A and FIG. 3B), the illustration and description thereof will be omitted.

The gate terminal section GT in the present embodiment includes the gate bus line GL formed on a dielectric substrate, the insulating layer covering the gate bus line GL, and the gate terminal upper connection section 19 g. The gate terminal upper connection section 19 g is in contact with the gate bus line GL within the contact hole CH2 formed in the insulating layer. In this example, the insulating layer covering the gate bus line GL includes the gate insulating layer 4 and the first insulating layer 11. The second insulating layer 17 is formed on the gate terminal upper connection section 19 g and the first insulating layer 11. The second insulating layer 17 includes an opening 18 g exposing a part of the gate terminal upper connection section 19 g. In this example, the opening 18 g of the second insulating layer 17 may be disposed so as to expose the entire contact hole CH2.

The source terminal section ST includes the source bus line SL formed on the dielectric substrate (here, on the gate insulating layer 4), the insulating layer covering the source bus line SL, and the source terminal upper connection section 19 s. The source terminal upper connection section 19 s is in contact with the source bus line SL within the contact hole CH3 formed in the insulating layer. In this example, the insulating layer covering the source bus line SL includes only the first insulating layer 11. The second insulating layer 17 extends over the source terminal upper connection section 19 s and the first insulating layer 11. The second insulating layer 17 includes an opening 18 s exposing a part of the source terminal upper connection section 19 s. The opening 18 s of the second insulating layer 17 may be disposed so as to expose the entire contact hole CH3.

The transfer terminal section PT includes a source connection wiring line 7 p formed from the same conductive film (source conductive film) as that of the source bus line SL, the first insulating layer 11 extending over the source connection wiring line 7 p, the transfer terminal upper connection section 19 p and the patch connection section 15 p formed on the first insulating layer 11.

Contact holes CH5 and CH6 are provided in the first insulating layer 11 to expose the source connection wiring line 7 p. The transfer terminal upper connection section 19 p is disposed on the first insulating layer 11 and within the contact hole CH5, and is in contact with the source connection wiring line 7 p within the contact hole CH5. The patch connection section 15 p is disposed on the first insulating layer 11 and within the contact hole CH6, and is in contact with the source connection wiring line 7 p within the contact hole CH6. The transfer terminal upper connection section 19 p is a transparent electrode formed of a transparent conductive film. The patch connection section 15 p is formed of the same conductive film as that of the patch electrode 15. Note that the upper connection sections 19 g, 19 s, and 19 p of the respective terminal sections may be formed of the same transparent conductive film.

The second insulating layer 17 extends over the transfer terminal upper connection section 19 p, the patch connection section 15 p, and the first insulating layer 11. The second insulating layer 17 includes an opening 18 p exposing a part of the transfer terminal upper connection section 19 p. In this example, the opening 18 p of the second insulating layer 17 is disposed so as to expose the entire contact hole CH5. In contrast, the patch connection section 15 p is covered with the second insulating layer 17.

In this way, in the present embodiment, the source connection wiring line 7 p formed in the source metal layer electrically connects the transfer terminal upper connection section 19 p of the transfer terminal section PT and the patch connection section 15 p. Although not illustrated in drawings, similar to the above-described embodiment, the transfer terminal upper connection section 19 p is connected to the slot electrode of the slot substrate 201 by a sealing resin containing conductive particles.

In the previously described embodiment, the contact holes CH1 to CH4 having different depths are collectively formed after the formation of the second insulating layer 17. For example, while the relatively thick insulating layers (the gate insulating layer 4, the first insulating layer 11 and the second insulating layer 17) are etched in the gate terminal section GT, only the second insulating layer 17 is etched in the transfer terminal section PT. Accordingly, there is a possibility that the conductive film (for example, a patch electrode conductive film) that serves as the base of the shallow contact holes is considerably damaged during etching.

In contrast, in the present embodiment, the contact holes CH1 to CH3, CH5, and CH6 are formed prior to formation of the second insulating layer 17. Since these contact holes are formed only in the first insulating layer 11 or in the layered film of the first insulating layer 11 and the gate insulating layer 4, the difference in depth of the collectively formed contact holes can be reduced more than in the previous embodiment. Accordingly, damage to the conductive film that serves as the base of the contact holes can be reduced. In particular, when an Al film is used for the patch electrode conductive film, since a favorable contact cannot be obtained in a case where the ITO film and the Al film are brought into direct contact with each other, a cap layer such as a MoN layer may be formed on the Al film in some cases. In these cases, there is the advantage that the thickness of the cap layer need not be increased to compensate for damage during etching.

Manufacturing Method of TFT Substrate 102

The TFT substrate 102 is manufactured by the following method, for example. FIG. 9 is a diagram illustrating an example of a manufacturing process of the TFT substrate 102. Note that in the following description, in cases where the material, thickness, formation method, or the like of each layer are the same as that of the TFT substrate 101 described above, the description thereof is omitted.

First, an alignment mark, a base insulating layer, a gate metal layer, a gate insulating layer, a semiconductor layer, a contact layer, and a source metal layer are formed on a dielectric substrate in the same manner as in the TFT substrate 101 to obtain a TFT. In the step of forming the source metal layer, in addition to the source and drain electrodes and the source bus line, the source connection wiring line 7 p is also formed from the source conductive film.

Next, the first insulating layer 11 is formed so as to cover the source metal layer. Subsequently, the first insulating layer 11 and the gate insulating layer 4 are collectively etched to form the contact holes CH1 to CH3, CH5, and CH6. During etching, each of the source bus line SL and the gate bus line GL functions as an etch stop. In this way, in the transmission and/or reception region R1, the contact hole CH1 that at least reaches the drain electrode of the TFT is formed in the first insulating layer 11. In addition, in the non-transmission and/or reception region R2, the contact hole CH2 that at least reaches the gate bus line GL is formed in the first insulating layer 11 and the gate insulating layer 4, and the contact hole CH3 that at least reaches the source bus line SL and contact holes CH5 and CH6 that at least reach the source connection wiring line 7 p are formed in the first insulating layer 11. The contact hole CH5 may be disposed in the seal region Rs and the contact hole CH6 may be disposed outside the seal region Rs. Alternatively, both may be disposed outside the seal region Rs.

Next, a transparent conductive film is formed on the first insulating layer 11 and within the contact holes CH1 to CH3, CH5, and CH6, and patterned. In this way, the gate terminal upper connection section 19 g in contact with the gate bus line GL within the contact hole CH2, the source terminal upper connection section 19 s in contact with the source bus line SL within the contact hole CH3, and the transfer terminal upper connection section 19 p in contact with the source connection wiring line 7 p within the contact hole CH5 are formed.

Next, a patch electrode conductive film is formed on the first insulating layer 11, the gate terminal upper connection section 19 g, the source terminal upper connection section 19 s, the transfer terminal upper connection section 19 p, and within the contact holes CH1 and CH6 and patterned. In this way, the patch electrode 15 in contact with the drain electrode 7D within the contact hole CH1 is formed in the transmission and/or reception region R1, and the patch connection section 15 p in contact with the source connection wiring line 7 p within the contact hole CH6 is formed in the non-transmission and/or reception region R2. Patterning of the patch electrode conductive film may be performed by wet etching. Here, an etchant capable of increasing the etching selection ratio between the transparent conductive film (ITO or the like) and the patch electrode conductive film (for example, an Al film) is used. In this way, when patterning the patch electrode conductive film, the transparent conductive film can function as an etch stop. Since the portions of the source bus line SL, the gate bus line GL, and the source connection wiring line 7 p exposed by the contact holes CH2, CH3, and CH5 are covered with an etch stop (transparent conductive film), they are not etched.

Subsequently, the second insulating layer 17 is formed. Thereafter, the second insulating layer 17 is patterned by, for example, dry etching using a fluorine-based gas. In this way, the opening 18 g exposing the gate terminal upper connection section 19 g, the opening 18 s exposing the source terminal upper connection section 19 s, and the opening 18 p exposing the transfer terminal upper connection section 19 p are provided in the second insulating layer 17. In this manner, the TFT substrate 102 is obtained.

Third Embodiment

The scanning antenna of a third embodiment will be described with reference to drawings. The TFT substrate in the scanning antenna of the present embodiment differs from the TFT substrate 102 illustrated in FIG. 8A to FIG. 8C in that the upper connection section made of a transparent conductive film is not provided in the transfer terminal section.

FIG. 10A to FIG. 10C are cross-sectional views illustrating the gate terminal section GT, the source terminal section ST, and the transfer terminal section PT, respectively, of a TFT substrate 103 in the present embodiment. Constituent elements similar to those in FIG. 8A to FIG. 8C are denoted by the same reference numerals. Since the structure of the antenna unit region U is similar to that of the above-described embodiments (FIG. 3A and FIG. 3B), the illustration and description thereof will be omitted.

The structures of the gate terminal section GT and the source terminal section ST are similar to the structures of the gate terminal section and the source terminal section of the TFT substrate 102 illustrated in FIG. 8A and FIG. 8B.

The transfer terminal section PT includes the patch connection section 15 p formed on the first insulating layer 11 and a protective conductive layer 23 layered on the patch connection section 15 p. The second insulating layer 17 extends over the protective conductive layer 23 and includes an opening 18 p exposing a part of the protective conductive layer 23. In contrast, the patch electrode 15 is covered with the second insulating layer 17.

Manufacturing Method of TFT Substrate 103

The TFT substrate 103 is manufactured by the following method, for example. FIG. 11 is a diagram illustrating an example of a manufacturing process of the TFT substrate 103. Note that in the following description, in cases where the material, thickness, formation method, or the like of each layer are the same as that of the TFT substrate 101 described above, the description thereof is omitted.

First, an alignment mark, a base insulating layer, a gate metal layer, a gate insulating layer, a semiconductor layer, a contact layer, and a source metal layer are formed on a dielectric substrate in the same manner as in the TFT substrate 101 to obtain a TFT.

Next, the first insulating layer 11 is formed so as to cover the source metal layer. Subsequently, the first insulating layer 11 and the gate insulating layer 4 are collectively etched to form the contact holes CH1 to CH3. During etching, each of the source bus line SL and the gate bus line GL functions as an etch stop. In this way, the contact hole CH1 that at least reaches the drain electrode of the TFT is formed in the first insulating layer 11, the contact hole CH2 that at least reaches the gate bus line GL is formed in the first insulating layer 11 and the gate insulating layer 4, and the contact hole CH3 that at least reaches the source bus line SL is formed in the first insulating layer 11. No contact hole is formed in the region where the transfer terminal section is formed.

Next, a transparent conductive film is formed on the first insulating layer 11 and within the contact holes CH1, CH2, and CH3, and patterned. In this way, the gate terminal upper connection section 19 g in contact with the gate bus line GL within the contact hole CH2 and the source terminal upper connection section 19 s in contact with the source bus line SL within the contact hole CH3 are formed. In the region where the transfer terminal section is formed, the transparent conductive film is removed.

Next, a patch electrode conductive film is formed on the first insulating layer 11, on the gate terminal upper connection section 19 g and the source terminal upper connection section 19 s, and within the contact hole CH1, and patterned. In this way, the patch electrode 15 in contact with the drain electrode 7D within the contact hole CH1 is formed in the transmission and/or reception region R1, and the patch connection section 15 p is formed in the non-transmission and/or reception region R2. Similar to the previous embodiments, an etchant capable of ensuring an etching selection ratio between the transparent conductive film (ITO or the like) and the patch electrode conductive film is used for patterning the patch electrode conductive film.

Subsequently, the protective conductive layer 23 is formed on the patch connection section 15 p. A Ti layer, an ITO layer, and an indium zinc oxide (IZO) layer (having a thickness of greater than or equal to 50 nm and less than or equal to 100 nm, for example), or the like can be used as the protective conductive layer 23. Here, a Ti layer (having a thickness of 50 nm, for example) is used as the protective conductive layer 23. Note that the protective conductive layer may be formed on the patch electrode 15.

Next, the second insulating layer 17 is formed. Thereafter, the second insulating layer 17 is patterned by, for example, dry etching using a fluorine-based gas. In this way, the opening 18 g exposing the gate terminal upper connection section 19 g, the opening 18 s exposing the source terminal upper connection section 19 s, and the opening 18 p exposing the protective conductive layer 23 are provided in the second insulating layer 17. In this manner, the TFT substrate 103 is obtained.

Structure of Slot Substrate 203

FIG. 12 is a schematic cross-sectional view for illustrating a transfer section that connects the transfer terminal section PT of the TFT substrate 103 and a terminal section IT of a slot substrate 203 in the present embodiment. In FIG. 12, the same reference numerals are attached to the same constituent elements as those in the embodiments described above.

First, the slot substrate 203 in this embodiment will be described. The slot substrate 203 includes the dielectric substrate 51, the third insulating layer 52 formed on the front surface of the dielectric substrate 51, the slot electrode 55 formed on the third insulating layer 52, and the fourth insulating layer 58 covering the slot electrode 55. The reflective conductive plate 65 is disposed opposing the rear surface of the dielectric substrate 51 with the dielectric layer (air layer) 54 interposed therebetween. The slot electrode 55 and the reflective conductive plate 65 function as walls of the waveguide 301.

The slot electrode 55 has a layered structure in which a Cu layer or an Al layer is the main layer 55M. In the transmission and/or reception region R1, a plurality of slots 57 are formed in the slot electrode 55. The structure of the slot electrode 55 in the transmission and/or reception region R1 is the same as the structure of the slot substrate 201 described above with reference to FIG. 6.

The terminal section IT is provided in the non-transmission and/or reception region R2. The terminal section IT includes an opening exposing the front surface of the slot electrode 55 provided in the fourth insulating layer 58. The exposed area of the slot electrode 55 serves as a contact surface 55 c. As described above, in the present embodiment, the contact surface 55 c of the slot electrode 55 is not covered with the fourth insulating layer 58.

In the transfer section, the protective conductive layer 23 covering the patch connection section 15 p of the TFT substrate 103 and the contact surface 55 c of the slot electrode 55 of the slot substrate 203 are connected with a resin (sealing resin) containing the conductive beads 71 therebetween.

As in the above-described embodiments, the transfer section in the present embodiment may be disposed at both the central portion and the peripheral portion of the scanning antenna, or may be disposed in only one of them. In addition, the transfer section may be disposed within the seal region Rs or may be disposed outside the seal region Rs (opposite to the liquid crystal layer).

In the present embodiment, no transparent conductive film is provided on the transfer terminal PT and the contact surface of the terminal section IT. Accordingly, the protective conductive layer 23 and the slot electrode 55 of the slot substrate 203 can be connected with a sealing resin containing conductive particles therebetween.

Furthermore, in the present embodiment, since the difference in the depth of the collectively formed contact holes is small in comparison with the first embodiment (FIG. 3A to FIG. 4C), the damage to the conductive film that serves as the base of the contact holes can be reduced.

Manufacturing Method of Slot Substrate 203

The slot substrate 203 is manufactured as follows. Since the material, the thickness, and the formation method of each layer are the same as those of the slot substrate 201, the description thereof is omitted.

First, the third insulating layer 52 and the slot electrode 55 are formed on the dielectric substrate in the same manner as the slot substrate 201, and a plurality of slots 57 are formed in the slot electrode 55. Next, the fourth insulating layer 58 is formed on the slot electrode 55 and within the slot. Subsequently, the opening 18 p is formed in the fourth insulating layer 58 so as to expose a region that will become the contact surface of the slot electrode 55. In this way, the slot substrate 203 is manufactured.

Internal Heater Structure

As described above, it is preferable that the dielectric anisotropy Δε_(M) of the liquid crystal material used for the antenna unit of the antenna be large. However, the viscosity of liquid crystal materials (nematic liquid crystals) having large dielectric anisotropies Δε_(M) is high, and the slow response speed may lead to problems. In particular, as the temperature decreases, the viscosity increases. The environmental temperature of a scanning antenna mounted on a moving body (for example, a ship, an aircraft, or an automobile) fluctuates. Accordingly, it is preferable that the temperature of the liquid crystal material can be adjusted to a certain extent, for example 30° C. or higher, or 45° C. or higher. The set temperature is preferably set such that the viscosity of the nematic liquid crystal material is about 10 cP (centipoise) or less.

In addition to the above structure, the scanning antenna according to the embodiments of the disclosure preferably has an internal heater structure. A resistance heating type heater that uses Joule heat is preferable as the internal heater. The material of the resistance film for the heater is not particularly limited to a specific material, but a conductive material having relatively high specific resistance such as ITO or IZO can be utilized, for example. In addition, to adjust the resistance value, a resistive film may be formed with thin lines or meshes made of a metal (e.g., nichrome, titanium, chromium, platinum, nickel, aluminum, and copper). Thin lines or meshes made of ITO and IZO may be also used. The resistance value may be set according to the required calorific value.

For example, to set the heat generation temperature of the resistive film to 30° C. for an area (roughly 90000 mm²) of a circle having a diameter of 340 mm with 100 V AC (60 Hz), the resistance value of the resistive film should be set to 139Ω, the current should be set to 0.7 A, and the power density should be set to 800 W/m². To set the heat generation temperature of the resistive film to 45° C. for the same area with 100 V AC (60 Hz), the resistance value of the resistive film should be set to 82Ω, the current should be set to 1.2 A, and the power density should be set to 1350 W/m².

The resistive film for the heater may be provided anywhere as long as it does not affect the operation of the scanning antenna, but to efficiently heat the liquid crystal material, the resistive film is preferably provided near the liquid crystal layer. For example, as illustrated in a TFT substrate 104 illustrated in FIG. 13A, a resistive film 68 may be formed on almost the entire surface of the dielectric substrate 1. FIG. 13A is a schematic plan view of the TFT substrate 104 including the heater resistive film 68. The resistive film 68 is covered with, for example, the base insulating film 2 illustrated in FIG. 3A. The base insulating film 2 is formed to have a sufficient dielectric strength.

The resistive film 68 preferably has openings 68 a, 68 b, and 68 c. When the TFT substrate 104 and the slot substrate are bonded to each other, the slots 57 are positioned to oppose the patch electrodes 15. At this time, the opening 68 a is disposed such that the resistive film 68 is not present within an area having a distance d from an edge of the slot 57. The distance d is 0.5 mm, for example. In addition, it is also preferable to dispose the opening 68 b under the auxiliary capacitance CS and to dispose the opening 68 c under the TFT.

Note that the size of the antenna unit U is, for example, 4 mm×4 mm. In addition, as illustrated in FIG. 13B, a width s2 of the slot 57 is 0.5 mm, a length s1 of the slot 57 is 3.3 mm, a width p2 of the patch electrode 15 in a width direction of the slot 57 is 0.7 mm, and a width p of the patch electrode 15 in a length direction of the slot 57 is 0.5 mm. Note that the size, shape, arrangement relationships, and the like of the antenna unit U, the slot 57, and the patch electrode 15 are not limited to the examples illustrated in FIG. 13A and FIG. 13B.

To further reduce the influence of the electric field from the heater resistive film 68, a shield conductive layer may be formed. The shield conductive layer is formed, for example, on the base insulating film 2 over almost the entire surface of the dielectric substrate 1. While the shield conductive layer need not include the openings 68 a and 68 b like in the resistive film 68, the opening 68 c is preferably provided therein. The shield conductive layer is formed of, for example, an aluminum layer, and is set to ground potential.

In addition, the resistive film preferably has a distribution of the resistance value so that the liquid crystal layer can be uniformly heated. A temperature distribution of the liquid crystal layer is preferably such that a difference between a maximum temperature and a minimum temperature (temperature fluctuation) is, for example, less than or equal to 15° C. When the temperature fluctuation exceeds 15° C., there are cases that phase difference modulation varies within the plane, and good quality beam formation cannot be achieved. Furthermore, when the temperature of the liquid crystal layer approaches the Tni point (for example, 125° C.), Δε_(M) becomes small, which is not preferable.

With reference to FIG. 14A, FIG. 14B, and FIG. 15A to FIG. 15C, the distribution of the resistance value in the resistive film will be described. FIG. 14A, FIG. 14B, and FIG. 15A to FIG. 15C illustrate schematic structures of resistance heating structures 80 a to 80 e and a current distribution. The resistance heating structure includes a resistive film and a heater terminal.

The resistance heating structure 80 a illustrated in FIG. 14A includes a first terminal 82 a, a second terminal 84 a, and a resistive film 86 a connected thereto. The first terminal 82 a is disposed at the center of the circle, and the second terminal 84 a is disposed along the entire circumference. Here, the circle corresponds to the transmission and/or reception region R1. When a DC voltage is applied between the first terminal 82 a and the second terminal 84 a, for example, a current IA flows radially from the first terminal 82 a to the second terminal 84 a. Accordingly, even though an in-plane resistance value is constant, the resistive film 86 a can uniformly generate heat. Of course, the direction of a current flow may be a direction from the second terminal 84 a to the first terminal 82 a.

The resistance heating structure 80 b illustrated in FIG. 14B includes a first terminal 82 b, a second terminal 84 b, and a resistive film 86 b connected thereto. The first terminal 82 b and the second terminal 84 b are disposed adjacent to each other along the circumference. A resistance value of the resistive film 86 b has an in-plane distribution such that an amount of heat generated per unit area by the current IA flowing between the first terminal 82 b and the second terminal 84 b in the resistive film 86 b is constant. In a case where the resistive film 86 b is formed of a thin line, for example, the in-plane distribution of the resistance value of the resistive film 86 may be adjusted by the thickness of the thin line and the density of the thin line.

The resistance heating structure 80 c illustrated in FIG. 15A includes a first terminal 82 c, a second terminal 84 c, and a resistive film 86 c connected thereto. The first terminal 82 c is disposed along the circumference of the upper half of the circle, and the second terminal 84 c is disposed along the circumference of the lower half of the circle. When the resistive film 86 c is constituted by thin lines extending vertically between the first terminal 82 c and the second terminal 84 c, for example, a thickness and a density of the thin lines near the center are adjusted such that the amount of heat generated per unit area by the current IA is constant in the plane.

The resistance heating structure 80 d illustrated in FIG. 15B includes a first terminal 82 d, a second terminal 84 d, and a resistive film 86 d connected thereto. The first terminal 82 d and the second terminal 84 d are provided so as to extend in the vertical direction and the horizontal direction, respectively, along the diameter of the circle. Although simplified in drawings, the first terminal 82 d and the second terminal 84 d are electrically insulated from each other.

In addition, the resistance heating structure 80 e illustrated in FIG. 15C includes a first terminal 82 e, a second terminal 84 e, and a resistive film 86 e connected thereto. Unlike the resistance heating structure 80 d, both the first terminal 82 e and the second terminal 84 e of the resistance heating structure 80 e include four portions extending from the center of the circle in four directions upward, downward, left, and right. The portions of the first terminal 82 e and the second terminal 84 e that form a 90 degree angle with each other are disposed such that the current IA flows clockwise.

In both of the resistance heating structure 80 d and the resistance heating structure 80 e, the thin line closer to the circumference is adjusted to be thick and have a higher density, for example, so that the closer to the circumference the more the current IA increases and the amount of heat generated per unit area becomes uniform within the plane.

Such an internal heater structure may automatically operate, for example, when it is detected that the temperature of the scanning antenna has fallen below a preset temperature. Of course, it may also operate in response to the operation of a user.

External Heater Structure

Instead of the internal heater structure described above, or in addition to the internal heater structure, the scanning antenna according to the embodiments of the disclosure may include an external heater structure. A resistance heating type heater that uses Joule heat is preferable as the external heater although various known heaters can be used. Assume that a part generating heat in the heater is a heater section. In the following description, an example in which a resistive film is used as the heater section is described. In the following description also, the resistive film is denoted by the reference numeral 68.

For example, the heater resistive film 68 is preferably disposed as in a liquid crystal panel 100Pa or 100Pb illustrated in FIGS. 16A and 16B. Here, the liquid crystal panels 100Pa and 100Pb include the TFT substrate 101, slot substrate 201, and liquid crystal layer LC provided therebetween in the scanning antenna 1000 illustrated in FIG. 1, and further includes a resistance heating structure including the resistive film 68 on an outer side of the TFT substrate 101. The resistive film 68 may be formed on a side of the dielectric substrate 1 of the TFT substrate 101 closer to the liquid crystal layer LC. However, such a configuration complicates a manufacturing process of the TFT substrate 101, and thus the resistive film 68 is preferably disposed on the outer side of the TFT substrate 101 (opposite to the liquid crystal layer LC).

The liquid crystal panel 100Pa illustrated in FIG. 16A includes the heater resistive film 68 formed on an outer surface of the dielectric substrate 1 of the TFT substrate 101 and a protective layer 69 a covering the heater resistive film 68. The protective layer 69 a may be omitted. The scanning antenna is housed in a case made of plastic, for example, and therefore, the resistive film 68 is not directly contacted by the user.

The resistive film 68 can be formed on the outer surface of the dielectric substrate 1 by use of, for example, a known thin film deposition technique (e.g., sputtering, CVD), a coating method, or a printing method. The resistive film 68 is patterned as needed. Patterning is performed through a photolithographic process, for example.

The material of the heater resistance film 68 is not particularly limited to a specific material as described above for the internal heater structure, but a conductive material having relatively high specific resistance such as ITO or IZO can be utilized, for example. In addition, to adjust the resistance value, the resistive film 68 may be formed with thin lines or meshes made of a metal (e.g., nichrome, titanium, chromium, platinum, nickel, aluminum, and copper). Thin lines or meshes made of ITO and IZO may be also used. The resistance value may be set according to the required calorific value.

The protective layer 69 a is made of an insulating material and formed to cover the resistive film 68. The protective layer 69 a may not be formed on a portion where the resistive film 68 is patterned and the dielectric substrate 1 is exposed. The resistive film 68 is patterned so as not to decrease the antenna performance as described later. In a case where a presence of the material forming the protective layer 69 a causes the antenna performance to decrease, the patterned protective layer 69 a is preferably used similar to the resistive film 68.

The protective layer 69 a may be formed by any of a wet process and a dry process. For example, a liquid curable resin (or precursor of resin) or a solution is applied on the surface of the dielectric substrate 1 on which the resistive film 68 is formed, and thereafter, the curable resin is cured to form the protective layer 69 a. The liquid resin or the resin solution is applied to the surface of the dielectric substrate 1 to have a predetermined thickness by various coating methods (e.g., using a slot coater, a spin coater, a spray) or various printing methods. After that, the resultant substrate is subjected to room temperature curing, thermal curing, or light curing depending on a kind of the resin to form the protective layer 69 a which is an insulating resin film. The insulating resin film may be patterned by a photolithographic process, for example.

A curable resin material is preferably used as a material for forming the protective layer 69 a. The curable resin material includes those of a thermal curing type resin material and a light curing type resin material. The thermal curing type includes a thermal cross-linking type and a thermal polymerization type.

Examples of the resin material of thermal cross-linking type include a combination of an epoxy-based compound (e.g., an epoxy resin) and amine-based compound, a combination of an epoxy-based compound and a hydrazide-based compound, a combination of an epoxy-based compound and an alcohol-based compound (e.g., including a phenol resin), a combination of an epoxy-based compound and a carboxylic acid-based compound (e.g., including an acid anhydride), a combination of an isocyanate-based compound and an amine-based compound, a combination of an isocyanate-based compound and a hydrazide-based compound, a combination of an isocyanate-based compound and an alcohol-based compound (e.g., including an urethane resin), and a combination of an isocyanate-based compound and a carboxylic acid-based compound. Examples of a cationic polymerization type adhesive include a combination of an epoxy-based compound and a cationic polymerization initiator (a representative cationic polymerization initiator: aromatic sulfonium salt). Examples of the resin material of radical polymerization type include a combination of a monomer and/or an oligomer containing a vinyl group of various acrylic, methacrylic, and urethane modified acrylic (methacrylic) resins and a radical polymerization initiator (a representative radical polymerization initiator: azo-based compound (e.g., azobisisobutyronitrile (AIBN))), and examples of the resin material of ring-opening polymerization type include an ethylene oxide-based compound, an ethyleneimine-based compound, and a siloxane-based compound. In addition, examples of the resin material may also include a maleimide resin, a combination of a maleimide resin and an amine, a combination of maleimide and a methacrylic compound, a bismaleimide-triazine resin, and a polyphenylene ether resin. Moreover, polyimide can be preferably used. Note that “polyimide” including polyamic acid that is a precursor of polyimide is used. Polyimide is used in combination with an epoxy-based compound or an isocyanate-based compound, for example.

In terms of a heat resistance, a chemical stability, and mechanical characteristics, the thermal curing type resin material is preferably used. Particularly, the resin material containing an epoxy resin or a polyimide resin is preferable, and in terms of the mechanical characteristics (in particular, a mechanical strength) and a hygroscopicity, the resin material containing a polyimide resin is preferable. A polyimide resin and an epoxy resin may be mixed to be used. A polyimide resin and/or an epoxy resin may be mixed with a thermoplastic resin and/or an elastomer. Furthermore, rubber-modified polyimide resin and/or epoxy resin may be mixed. A thermoplastic resin or an elastomer can be mixed to improve flexibility or toughness. Even when the rubber-modified resin is used, the same effect can be obtained.

A cross-linking reaction and/or a polymerization reaction of the light curing type material is caused by an ultraviolet light or a visible light, and the light curing type material cures. The light curing type includes a radical polymerization type and a cationic polymerization type, for example. Representative examples of the radical polymerization type material include a combination of an acrylic resin (epoxy modified acrylic resin, urethane modified acrylic resin, silicone modified acrylic resin) and a photopolymerization initiator. Examples of an ultraviolet radical polymerization initiator include an acetophenone type initiator and a benzophenone type initiator. Examples of a visible light radical polymerization initiator include a benzylic type initiator and a thioxanthone type initiator. Representative examples of a cationic polymerization type material include a combination of an epoxy-based compound and a photo cationic polymerization initiator. Examples of a photo cationic polymerization initiator include an iodonium salt-based compound. A resin material having both light curing and thermal curing characteristics can be used also.

The liquid crystal panel 100Pb illustrated in FIG. 16B is different from the liquid crystal panel 100Pa in that the liquid crystal panel 100Pb further includes an adhesive layer 67 between the resistive film 68 and the dielectric substrate 1. Moreover, the liquid crystal panel 100Pb is different from the liquid crystal panel 100Pa in that the protective layer 69 b is formed using a polymer film or glass plate fabricated in advance.

For example, the liquid crystal panel 100Pb including the protective layer 69 b formed of a polymer film is manufactured as below.

First, an insulating polymer film that will become the protective layer 69 b is prepared. Examples of a polymer film include a polyester film made of polyethylene terephthalate, polyethylene naphthalate or the like, and a film made of super engineering plastic such as polyphenylene sulfone, polyimide, or polyamide. A thickness of the polymer film (that is, a thickness of the protective layer 69 b) is greater than or equal to 5 μm and less than or equal to 200 μm, for example.

The resistive film 68 is formed on one surface of this polymer film. The resistive film 68 can be formed by the above method. The resistive film 68 may be patterned, and the polymer film may be also patterned as needed.

The polymer film on which the resistive film 68 is formed (that is, a member integrally formed of the protective layer 69 b and the resistive film 68) is bonded to the dielectric substrate 1 with an adhesive. Examples of the adhesive include the same curable resin as the curable resin used to form the protective layer 69 a described above. Furthermore, a hot-melt type resin material (adhesive) can be used. The hot-melt type resin material contains a thermoplastic resin as a main component, and melts by heating and solidifies by cooling. Examples of the hot-melt type resin material include polyolefin-based (e.g., polyethylene, polypropylene), polyamide-based, and ethylene vinyl acetate-based resins. A reactive urethane-based hot-melt resin material (adhesive) is also available. In terms of adhesive and durability, the reactive urethane-based resin is preferable.

The adhesive layer 67 may be patterned similar to the resistive film 68 and the protective layer (polymer film) 69 b. However, the adhesive layer 67 needs only fix the resistive film 68 and the protection layer 69 b to the dielectric substrate 1, and may be smaller than the resistive film 68 and the protective layer 69 b.

In place of the polymer film, the glass plate may be also used to form the protective layer 69 b. A manufacturing process may be the same as the case of using the polymer film. A thickness of the glass plate is preferably less than or equal to 1 mm and further preferably less than or equal to 0.7 mm. A lower limit of the thickness of the glass plate is not specifically specified, but in terms of handling, the thickness of the glass plate is preferably greater than or equal to 0.3 mm.

In the liquid crystal panel 100Pb illustrated in FIG. 16B, the resistive film 68 formed on the protective layer (polymer film or glass plate) 69 b is fixed to the dielectric substrate 1 via the adhesive layer 67, but the resistive film 68 needs only be disposed in contact with the dielectric substrate 1 and the resistive film 68 and the protective layer 69 b are not necessarily fixed (bonded) to the dielectric substrate 1. In other words, the adhesive layer 67 may be omitted. For example, the polymer film on which the resistive film 68 is formed (that is, a member integrally formed of the protective layer 69 b and the resistive film 68) may be disposed such that the resistive film 68 is brought into contact with the dielectric substrate 1 and is pressed against the dielectric substrate 1 with the case housing the scanning antenna. For example, since the thermal contact resistance possibly increases when the polymer film on which the resistive film 68 is formed is merely disposed only, the polymer film is preferably pressed against the dielectric substrate to decrease the thermal contact resistance. Using such a configuration allows the member integrally formed of the resistive film 68 and the protective layer (polymer film or glass plate) 69 b to be detachable.

Note that in a case where the resistive film 68 (and the protective layer 69 b) is patterned as described later, the resistive film 68 (and the protective layer 69 b) is preferably fixed to the dielectric substrate 1 to a degree not to shift in a position with respect to the TFT substrate so that the antenna performance does not decrease.

The heater resistive film 68 may be provided anywhere as long as it does not affect the operation of the scanning antenna, but to efficiently heat the liquid crystal material, the resistive film is preferably provided near the liquid crystal layer. Therefore, the heater resistive film 68 is preferably provided on the outer side of the TFT substrate 101 as illustrated in FIGS. 16A and 16B. In addition, the resistive film 68 directly provided on the outer side of the dielectric substrate 1 of the TFT substrate 101 as illustrated in FIG. 16A is preferable, because an energy efficiency is higher, and controllability of the temperature is higher than those in a case in which the resistive film 68 is provided on the outer side of the dielectric substrate 1 with the adhesive layer 67 therebetween as illustrated in FIG. 16B.

For example, the resistive film 68 may be formed on almost the entire surface of the dielectric substrate 1 of the TFT substrate 104 illustrated in FIG. 13A. The resistive film 68 preferably includes the openings 68 a, 68 b, and 68 c as described for the internal heater structure.

The protective layers 69 a and 69 b may be formed on the entire surface to cover the resistive film 68. As described above, in a case where the protective layer 69 a or 69 b has an adverse effect on antenna characteristics, openings corresponding to the openings 68 a, 68 b, and 68 c of the resistive film 68 may be provided. In this case, the openings of the protective layer 69 a or 69 b are formed inside the openings 68 a, 68 b, and 68 c of the resistive film 68.

To further reduce the influence of the electric field from the heater resistive film 68, a shield conductive layer may be formed. The shield conductive layer is formed on the side of the resistive film 68 closer to the dielectric substrate 1 with an insulating film therebetween, for example. The shield conductive layer is formed on almost the entire surface of the dielectric substrate 1. While the shield conductive layer need not include the openings 68 a and 68 b like in the resistive film 68, the opening 68 c is preferably provided therein. The shield conductive layer is formed of, for example, an aluminum layer, and is set to ground potential. In addition, the resistive film preferably has a distribution of the resistance value so that the liquid crystal layer can be uniformly heated. These structures are similar to the structures of the internal heater structure described above.

The resistive film needs only heat the liquid crystal layer LC in the transmission and/or reception region R1, and may be provided on an area corresponding to the transmission and/or reception region R1 as an example described above. However, the structure of the resistive film is not limited to this structure. For example, as illustrated in FIG. 2A, in a case where the TFT substrate 101 has an outline capable of defining a rectangular area encompassing the transmission and/or reception region R1, the resistive film may be provided on an area corresponding to the rectangular area encompassing the transmission and/or reception region R1. Of course, the outline of the resistive film is not limited to a rectangle, and may be any shape encompassing the transmission and/or reception region R1.

In the above example, the resistive film is disposed on the outer side of the TFT substrate 101, but the resistive film may be disposed on an outer side of the slot substrate 201 (opposite to the liquid crystal layer LC). In this case also, the resistive film may be formed directly on the dielectric substrate 51 similar to the liquid crystal panel 100Pa in FIG. 16A, or the resistive film formed on the protective layer (polymer film or glass plate) with the adhesive layer therebetween may be fixed to the dielectric substrate 51 similar to the liquid crystal panel 100Pb in FIG. 16B. Alternatively, the protective layer on which the resistive film is formed without the adhesive layer (that is, the member integrally formed of the protective layer and the resistive film) may be disposed such that the resistive film is in contact with the dielectric substrate 51. For example, since the thermal contact resistance possibly increases in a case where the polymer film on which the resistive film is formed is merely disposed only, the polymer film is preferably pressed against the dielectric substrate 51 to decrease the thermal contact resistance. Using such a configuration allows the member integrally formed of the resistive film and the protective layer (polymer film or glass plate) to be detachable. Note that in a case where the resistive film (and the protective layer) is patterned, the resistive film (and the protective layer) is preferably fixed to the dielectric substrate to a degree not to shift in a position with respect to the slot substrate so that the antenna performance does not decrease.

In a case where the resistive film is disposed on the outer side of the slot substrate 201, openings are preferably provided in the resistive film at positions corresponding to the slots 57. The resistive film has preferably a thickness enough to transmit microwaves.

Here, the example in which the resistive film is used as the heater section is described, but other than the example, a nichrome line (e.g., winding wire), an infrared light heater section, and the like may be used as the heater section, for example. In the cases like these also, the heater section is preferably disposed not to decrease the antenna performance.

Such an external heater structure may automatically operate, for example, when it is detected that the temperature of the scanning antenna has fallen below a preset temperature. Of course, it may also operate in response to the operation of a user.

As a temperature control device for making the external heater structure automatically operate, various known thermostats can be used, for example. For example, a thermostat using bimetal may be connected between one of two terminals connected with the resistive film and a power source. Of course, a temperature control device may be used which supplies current to the external heater structure from the power source to prevent the temperature from falling below a preset temperature by use of a temperature sensor.

Driving Method

Since an antenna unit array of the scanning antenna according to the embodiments of the disclosure has a structure similar to that of an LCD panel, line sequential driving is performed in the same manner as an LCD panel. However, in a case where existing driving methods for LCD panels are applied, the following problems may occur. Problems that may occur in the scanning antenna will be described with reference to the equivalent circuit diagram of one antenna unit of the scanning antenna illustrated in FIG. 17.

First, as mentioned above, since the specific resistance of liquid crystal materials having large dielectric anisotropies Δε_(M) (birefringence Δn with respect to visible light) in the microwave range is low, in a case where driving methods for LCD panels are applied as is, the voltage applied to the liquid crystal layer cannot be sufficiently maintained. Then, the effective voltage applied to the liquid crystal layer decreases, and the electrostatic capacitance value of the liquid crystal capacitance does not reach the target value.

In this way, when the voltage applied to the liquid crystal layer deviates from the predetermined value, the direction in which the gain of the antenna becomes maximum deviates from the intended direction. Then, for example, communication satellites cannot be accurately tracked. To prevent this, an auxiliary capacitance CS is provided electrically in parallel with the liquid crystal capacitance Clc, and the capacitance value C-Ccs of the auxiliary capacitance CS is sufficiently increased. The capacitance value C-Ccs of the auxiliary capacitance CS is preferably set appropriately such that the voltage retention rate of the liquid crystal capacitance Clc is 90% or greater.

In addition, when a liquid crystal material having a low specific resistance is utilized, a voltage reduction due to the interface polarization and/or the orientation polarization also occurs. To prevent the voltage drop due to these polarizations, it is conceivable to apply a sufficiently high voltage in anticipation of the voltage drop. However, when a high voltage is applied to a liquid crystal layer having a low specific resistance, a dynamic scattering effect (DS effect) may occur. The DS effect is caused by a convection of ionic impurities in the liquid crystal layer, and the dielectric constant ε_(M) of the liquid crystal layer approaches an average value ((ε_(M)//+2ε_(M)⊥)/3). Also, to control the dielectric constant ε_(M) of the liquid crystal layer in multiple stages (multiple gray scales), it is not always possible to apply a sufficiently high voltage.

To suppress the above-described DS effect and/or the voltage drop due to the polarization, the polarity inversion period of the voltage applied to the liquid crystal layer may be sufficiently shortened. As is well known, in a case where the polarity inversion period of the applied voltage is shortened, a threshold voltage at which the DS effect occurs becomes higher. Accordingly, the polarity inversion frequency may be determined such that the maximum value of the voltage (absolute value) applied to the liquid crystal layer is less than the threshold voltage at which the DS effect occurs. For the polarity inversion frequency of 300 Hz or greater, even in a case where a voltage with an absolute value of 10 V is applied to a liquid crystal layer having a specific resistance of 1×10¹⁰ Ω·cm and a dielectric anisotropy Δε; (@1 kHz) of about −0.6, a good quality operation can be ensured. In addition, in a case where the polarity inversion frequency (typically equal to twice the frame frequency) is 300 Hz or greater, the voltage drop caused by the polarization is also suppressed. From the viewpoint of power consumption and the like, the upper limit of the polarity inversion period is preferably about less than or equal to 5 KHz.

As described above, since the viscosity of the liquid crystal material depends on the temperature, it is preferable that the temperature of the liquid crystal layer be appropriately controlled. The physical properties and driving conditions of the liquid crystal material described here are values under the operating temperature of the liquid crystal layer. Conversely, the temperature of the liquid crystal layer is preferably controlled such that it can be driven under the above conditions.

An example of a waveform of a signal used for driving the scanning antenna will be described with reference to FIG. 18A to FIG. 18G. Note that FIG. 18D illustrates the waveform of the display signal Vs (LCD) supplied to the source bus line of the LCD panel for comparison.

FIG. 18A illustrates the waveform of a scanning signal Vg supplied to a gate bus line G-L1, FIG. 18B illustrates the waveform of a scanning signal Vg supplied to a gate bus line G-L2, FIG. 18C illustrates the waveform of a scanning signal Vg supplied to a gate bus line G-L3, FIG. 18E illustrates the waveform of a data signal Vda supplied to the source bus line, FIG. 18F illustrates the waveform of a slot voltage Vidc supplied to the slot electrode of the slot substrate (slot electrode), and FIG. 18G illustrates the waveform of the voltage applied to the liquid crystal layer of each antenna unit.

As illustrates in FIG. 18A to FIG. 18C, the voltage of the scanning signal Vg supplied to the gate bus line sequentially changes from a low level (VgL) to a high level (VgH). VgL and VgH can be appropriately set according to the characteristics of the TFT. For example, VgL=from −5 V to 0 V, and VgH=+20 V. Also, VgL=−20 V and VgH=+20 V are possible. A period from the time when the voltage of the scanning signal Vg of a particular gate bus line switches from the low level (VgL) to the high level (VgH) until the time when the voltage of the next gate bus line switches from VgL to VgH will be referred to as one horizontal scan period (1H). In addition, the period during which the voltage of each gate bus line is at the high level (VgH) will be referred to as a selection period PS. In this selection period PS, the TFTs connected to the respective gate bus lines are turned on, and the current voltage of the data signal Vda supplied to the source bus line is supplied to the corresponding patch electrode. The data signal Vda is, for example, from −15 V to 15 V (an absolute value is 15 V), and, for example, a data signal Vda having different absolute values corresponding to 12 gray scales, or preferably corresponding to 16 gray scales is used.

Here, a case is exemplified where an intermediate voltage is applied to all antenna units. That is, it is assumed that the voltage of the data signal Vda is constant with respect to all antenna units (assumed to be connected to m gate bus lines). This corresponds to the case where the gray levels are displayed on the LCD panel over the whole surface thereof. At this time, dot inversion driving is performed in the LCD panel. That is, in each frame, the display signal voltage is supplied such that the polarities of adjacent pixels (dots) are opposite to each other.

FIG. 18D illustrates the waveform of the display signal of the LCD panel on which the dot inversion driving is performed. As illustrated in FIG. 18D, the polarity of Vs (LCD) is reversed every 1H. The polarity of the Vs (LCD) supplied to a source bus line adjacent to a source bus line supplied with the Vs (LCD) having this waveform is opposite to the polarity of the Vs (LCD) illustrated in FIG. 18D. Furthermore, the polarity of the display signal supplied to all the pixels is inverted for each frame. In the LCD panels, it is difficult to perfectly match the magnitude of the effective voltage applied to the liquid crystal layer between the positive polarity and the negative polarity, and further, the difference in effective voltage becomes a difference in luminance, which is observed as flicker. To make this flicker less noticeable, the pixels (dots) to which voltages of different polarities are applied are spatially dispersed in each frame. Typically, by performing the dot inversion driving, the pixels (dots) having different polarities are arranged in a checkered pattern.

In contrast, in the scanning antenna, the flicker itself is not problematic. That is, it is sufficient for the electrostatic capacitance value of the liquid crystal capacitance to be an intended value, and the spatial distribution of the polarity in each frame is not problematic. Accordingly, from the perspective of low power consumption or the like, it is preferable to reduce the number of times of polarity inversion of the data signal Vda supplied from the source bus line; that is, to lengthen the period of polarity inversion. For example, as illustrated in FIG. 18E, the period of polarity inversion may be set to 10 H (such that polarity inversion occurs every 5 H). Of course, in a case where the number of antenna units connected to each source bus line (typically equal to the number of gate bus lines) is m, the period of polarity inversion of the data signal Vda may be 2 m·H (polarity inversion occurs each m·H). The period of polarity inversion of the data signal Vda may be equal to 2 frames (a polarity inversion occurs each frame).

In addition, the polarity of the data signal Vda supplied from all the source bus lines may be the same. Accordingly, for example, in a particular frame, a positive polarity data signal Vda may be supplied from all the source bus lines, and in the next frame, a negative polarity data signal Vda may be supplied from all the source bus lines.

Alternatively, the polarities of the data signals Vda supplied from the adjacent source bus lines may be opposite to each other. For example, in a particular frame, a positive polarity data signal Vda is supplied from odd-numbered source bus lines, and a negative polarity data signal Vda may be supplied from even-numbered source bus lines. Then, in the next frame, the negative polarity data signal Vda is supplied from the odd-numbered source bus lines, and the positive polarity data signal Vda is supplied from the even-numbered source bus lines. In the LCD panels, such a driving method is referred to as source line inversion driving. In a case where the data signals Vda supplied from adjacent source bus line are made to have opposite polarity, by connecting (short-circuiting) adjacent source bus lines to each other before inverting the polarity of the data signals Vda supplied between frames, it is possible to cancel electric charges stored in the liquid crystal capacitance between adjacent columns. Accordingly, an advantage can be obtained such that the amount of electric charge supplied from the source bus line in each frame can be reduced.

As illustrated in FIG. 18F, the voltage Vidc of the slot electrode is, for example, a DC voltage, and is typically a ground potential. Since the capacitance value of the capacitance (liquid crystal capacitance and auxiliary capacitance) of the antenna units is greater than the capacitance value of the pixel capacitance of the LCD panel (for example, about 30 times in comparison with 20-inch LCD panels), there is no affect from a pull-in voltage due to a parasitic capacitance of the TFT, and even in a case where the voltage Vide of the slot electrode is the ground potential and the data signal Vda is a positive or negative symmetrical voltage with reference to the ground potential, the voltage supplied to the patch electrode is a positive and negative symmetrical voltage. In the LCD panels, although the positive and negative symmetrical voltages are applied to the pixel electrode by adjusting the voltage (common voltage) of the counter electrode in consideration of the pull-in voltage of the TFT, this is not necessary for the slot voltage of the scanning antenna, and ground potential may be used. Also, although not illustrated in FIG. 18A to FIG. 18G, the same voltage as the slot voltage Vide is supplied to the CS bus line.

Since the voltage applied to the liquid crystal capacitance of each antenna unit is the voltage of the patch electrode with respect to the voltage Vide (FIG. 18F) of the slot electrode (that is, the voltage of the data signal Vda illustrated in FIG. 18E), when the slot voltage Vide is the ground potential, as illustrated in FIG. 18G, the voltage coincides with the waveform of the data signal Vda illustrated in FIG. 18E.

The waveform of the signal used for driving the scanning antenna is not limited to the above example. For example, as described below with reference to FIG. 19A to FIG. 19E and FIG. 20A to FIG. 20E, a Viac having an oscillation waveform may also be used as the voltage of the slot electrode.

For example, signals such as those exemplified in FIG. 19A to FIG. 19E can be used. In FIG. 19A to FIG. 19E, although the waveform of the scanning signal Vg supplied to the gate bus line is omitted, the scanning signal Vg described with reference to FIG. 18A to FIG. 18C is also used here.

As illustrated in FIG. 19A, similar to that illustrated in FIG. 18E, a case where the waveform of the data signal Vda is inverted in polarity at a 10H period (every 5 H) will be exemplified. Here, a case where an amplitude is the maximum value |Vda_(max)| is illustrated as the data signal Vda. As described above, the waveform of the data signal Vda may be inverted in polarity at a two frame period (each frame).

Here, as illustrated in FIG. 19C, the voltage Viac of the slot electrode is an oscillation voltage such that the polarity of the voltage Viac of the slot electrode is opposite to the polarity of the data signal Vda (ON), and the oscillation period of the slot electrode is the same as that of data signal Vda (ON). The amplitude of the voltage Viac of the slot electrode is equal to the maximum value |Vda_(max)| of the amplitude of the data signal Vda. That is, the slot voltage Viac is set to a voltage that oscillates between −Vda_(max) and +Vda_(max) with the same period of polarity inversion as that of the data signal Vda (ON) and opposite polarity (the phase differs by 180°).

Since a voltage Vie applied to the liquid crystal capacitance of each antenna unit is the voltage of the patch electrode with respect to the voltage Viac (FIG. 19C) of the slot electrode (that is, the voltage of the data signal Vda (ON) illustrated in FIG. 19A), when the amplitude of the data signal Vda oscillates at ±Vda_(max), the voltage applied to the liquid crystal capacitance has a waveform that oscillates with an amplitude twice Vda_(max) as illustrated in FIG. 19D. Accordingly, the maximum amplitude of the data signal Vda required to make the maximum amplitude of the voltage Vlc applied to the liquid crystal capacitance ±Vda_(max) is ±Vda_(max)/2.

Since the maximum amplitude of the data signal Vda can be halved by using such a slot voltage Viac, there is the advantage that a general-purpose driver IC with a breakdown voltage of 20 V or less can be used as a driver circuit for outputting the data signal Vda, for example.

Note that, as illustrated in FIG. 19E, to make the voltage Vlc (OFF) applied to the liquid crystal capacitance of each antenna unit zero, as illustrated in FIG. 19B, it may be preferable for the data signal Vda (OFF) to have the same waveform as that of the slot voltage Viac.

Consider, for example, a case where the maximum amplitude of the voltage Vlc applied to the liquid crystal capacitance is ±15 V. When the Vidc illustrated in FIG. 18F is used as the slot voltage and Vidc=0 V, the maximum amplitude of Vda illustrated in FIG. 18E becomes ±15 V. In contrast, when the Viac illustrated in FIG. 19C is used as the slot voltage and the maximum amplitude of Viac is ±7.5 V, the maximum amplitude of Vda (ON) illustrated in FIG. 19A becomes ±7.5 V.

When the voltage Vlc applied to the liquid crystal capacitance is 0 V, the Vda illustrated in FIG. 18E may be set to 0 V, and the maximum amplitude of the Vda (OFF) illustrated in FIG. 19B may be set to ±7.5 V.

In a case where the Viac illustrated in FIG. 19C is utilized, the amplitude of the voltage Vlc applied to the liquid crystal capacitance is different from the amplitude of Vda, and therefore appropriate conversions are necessary.

Signals such as those exemplified in FIG. 20A to FIG. 20E can also be used. The signals illustrated in FIG. 20A to FIG. 20E are the same as the signals illustrated in FIG. 19A to FIG. 19E in that the voltage Viac of the slot electrode is an oscillation voltage such that the oscillation phase thereof is shifted by 180° from the oscillation phase of the data signal Vda (ON) as illustrated FIG. 20C. However, as illustrated in each of FIG. 20A to FIG. 20C, all of the data signals Vda (ON), Vda (OFF) and the slot voltage Viac are voltages oscillating between 0 V and a positive voltage. The amplitude of the voltage Viac of the slot electrode is equal to the maximum value |Vda_(max)| of the amplitude of the data signal Vda.

When such a signal is utilized, the driving circuit only needs to output a positive voltage, which contributes to cost reduction. As described above, even in a case where a voltage oscillating between 0 V and a positive voltage is used, as illustrated in FIG. 20D, the polarity of the voltage Vie (ON) applied to the liquid crystal capacitance is inverted. In the voltage waveform illustrated in FIG. 20D, +(positive) indicates that the voltage of the patch electrode is higher than the slot voltage, and − (negative) indicates that the voltage of the patch electrode is lower than the slot voltage. That is, the direction (polarity) of the electric field applied to the liquid crystal layer is reversed similarly to the other examples. The amplitude of the voltage Vie (ON) applied to the liquid crystal capacitance is Vda_(max).

Note that, as illustrated in FIG. 20E, to make the voltage Vlc (OFF) applied to the liquid crystal capacitance of each antenna unit zero, as illustrated in FIG. 20B, it may be preferable for the data signal Vda (OFF) to have the same waveform as that of the slot voltage Viac.

The driving method described with reference to FIG. 19A to FIG. 19E and FIG. 20A to FIG. 20E of oscillating (inverting) the voltage Viac of the slot electrodes corresponds to a driving method of inverting the counter voltage in the driving method of LCD panels (sometimes referred to as a “common inversion drive”). In the LCD panels, since the flicker cannot be sufficiently suppressed, the common inversion drive is not utilized. In contrast, in the scanning antennas, since the flicker does not matter, the slot voltage can be reversed. Oscillation (inversion) is performed in each frame, for example (the 5H in FIG. 19A to FIG. 19E and FIG. 20A to FIG. 20E is set to 1 V (vertical scanning period or frame)).

In the above description, although an example of the voltage Viac of the slot electrode is described in which one voltage is applied; that is, an example in which a common slot electrode is provided for all patch electrodes, the slot electrode may be divided corresponding to one row or two or more rows of the patch electrode. Here, a row refers to a set of patch electrodes connected to one gate bus line with a TFT therebetween. By dividing the slot electrode into a plurality of row portions in this way, the polarities of the voltages of the respective portions of the slot electrode can be made independent from each other. For example, in a freely-selected frame, the polarity of the voltage applied to the patch electrodes can be reversed between the patch electrodes connected to adjacent gate bus lines. In this way, it is possible to perform row inversion in which the polarity is inverted not only for each single row (1H inversion) of the patch electrode, but also m row inversion (mH inversion) in which the polarity is inverted for every two or more rows. Of course, row inversion and frame inversion can be combined.

From the viewpoint of simplicity of driving, it is preferable that the polarity of the voltage applied to the patch electrode be the same in any frame, and the polarity be reversed every frame.

Example of Antenna Unit Array and Connection of Gate Bus Line and Source Bus Line

In the scanning antenna according to the embodiments of the disclosure, the antenna units are arranged concentrically, for example.

For example, in a case where the antenna units are arranged in m concentric circles, one gate bus line is provided for each circle, for example, such that a total of m gate bus lines is provided. For example, assuming that the outer diameter of the transmission and/or reception region R1 is 800 mm, m is 200, for example. Assuming that the innermost gate bus line is the first one, n (30, for example) antenna units are connected to the first gate bus line and nx (620, for example) antenna units are connected to the mth gate bus line.

In such an arrangement, the number of antenna units connected to each gate bus line is different. In addition, although m antenna units are connected to the nx number of source bus lines connected to the nx number of antenna units that constitute the outermost circle, the number of antenna units connected to the source bus line connected to the antenna units that constitute the inner circle becomes less than m.

In this way, the arrangement of antenna units in the scanning antenna is different from the arrangement of pixels (dots) in the LCD panel, and the number of connected antenna units differs depending on the gate bus line and/or source bus line. Accordingly, in a case where the capacitances (liquid crystal capacitances+auxiliary capacitances) of all the antenna units are set to be the same, depending on the gate bus line and/or the source bus line, the electrical loads of the antenna units connected thereto differ. In such a case, there is a problem where variations occur in the writing of the voltage to the antenna unit.

Accordingly, to prevent this, the capacitance value of the auxiliary capacitance is preferably adjusted, or the number of antenna units connected to the gate bus line and/or the source bus line is preferably adjusted, for example, to make the electrical loads of the antenna units connected to the gate bus lines and the source bus lines substantially the same.

Inspection Method of Scanning Antenna

Next, a description is given of an inspection method for detecting a malfunction of the scanning antenna.

As described above, in the scanning antenna, the voltage applied to the liquid crystal layer LC for each antenna unit U is controlled, and thereby, the liquid crystal alignment of the antenna unit U is controlled to change the dielectric constant M for microwaves. For example, in a case where short circuit or disconnection of the wiring line occurs, the liquid crystal alignment of the antenna unit U connected with the wiring line is not properly controlled, which causes a decrease in directivity, sensitivity, and the like of the scanning antenna. For this reason, in an inspection for detecting the malfunction of the scanning antenna, it is preferable to estimate the alignment state of the liquid crystal for each antenna unit U to detect an alignment failure.

In the transmissive LCD 900 (FIGS. 40A and 40B), the pixel electrode 914 and the counter electrode 924 which are disposed with the liquid crystal layer 930 interposed therebetween are transparent. Therefore, the alignment state of the liquid crystal layer 930 can be directly observed on the basis of whether the visible light is transmitted therethrough. However, the scanning antenna 1000 (in FIG. 1) according to the present embodiment uses a metal electrode which is non-transparent as the patch electrode 15 and slot electrode 55 configured to control the alignment of the liquid crystals. For this reason, an alignment state of a portion of the liquid crystal layer LC between the patch electrode 15 and a portion of the slot electrode 55 other than the slot 57 (hereinafter, “solid portion”) is difficult to directly be observed, which raises a problem that it is difficult to easily detect whether alignment control for each antenna unit U can be made. To deal with this problem, the present inventors have found a method for easily and efficiently inspecting the liquid crystal alignment of the antenna unit U (hereinafter, abbreviated as the “alignment inspection method”).

The alignment inspection method according to the present embodiment includes inspecting the quality of the liquid crystal alignment for each antenna unit U by observing an alignment state of liquid crystal molecules caused by an oblique electric field generated between the patch electrode 15 and the solid portion, or by disposing an inspection transparent electrode in the antenna unit U to observe the alignment state of the liquid crystal molecules between the transparent electrode and the patch electrode 15 or the solid portion. Hereinafter, an alignment inspection method using the oblique electric field is referred to as “alignment inspection I”, and an alignment inspection method using the inspection transparent electrode is referred to as “alignment inspection II”.

Alignment Inspection I

In the following description, of the patch electrode 15 and the solid portion of the slot electrode 55, an electrode located closer to an observer in the alignment inspection may be called an “upper electrode UE” and the other electrode opposite thereto may be called a “lower electrode LE” in some cases.

FIG. 21A is a cross-sectional view schematically illustrating the alignment state of the antenna unit in the scanning antenna 1000, and FIG. 21B is a plan view exemplarily illustrating a result of observing the alignment state of each antenna unit. Here, a description is given of an example in which the liquid crystal alignment is observed from a side of the slot substrate.

The scanning antenna 1000 includes a plurality of antenna units. FIGS. 21A and 21B exemplarily illustrate two antenna units U and U2. The antenna unit U1 is illustrated as an example in which a voltage is applied to the liquid crystal layer LC and the liquid crystal molecules are favorably aligned, and the antenna unit U2 is illustrated as an example in which no voltage is applied to the liquid crystal layer LC from any cause and the liquid crystal molecules do not have a predetermined alignment (or have the alignment failure).

The scanning antenna 1000 includes, as described above with reference to FIG. 1, the TFT substrate 101 including a plurality of TFTs (not illustrated), a plurality of patch electrodes 15, and the like, the slot substrate 201 including the slot electrode 55 formed on a front surface (a first main surface) thereof, the liquid crystal layer LC provided between the TFT substrate 101 and the slot substrate 201, and the reflective conductive plate (not illustrated) disposed on a second main surface (rear surface) of the slot substrate 201. The plurality of TFTs and the plurality of patch electrodes 15 are associated with the antenna units. The slot electrode 55 includes a plurality of slots (openings) 57 and the solid portion (a portion other than the slots 57) 56 formed of a metal film. The plurality of slots 57 are disposed to correspond to the patch electrodes 15.

When viewed from the normal direction of the TFT substrate 101 and the slot substrate 201, in each of the antenna units U1 and U2, the patch electrode 15 is disposed across the slot 57 in a first direction x and overlaps the solid portion 56 at both sides of the slot 57. The first direction x may be called a slot width direction, and a second direction y perpendicular to the first direction x may be called a slot length direction herein in some cases.

In this example, an Al electrode having a thickness of 5 μm or a Cu electrode having a thickness of 3 μm is used as the slot electrode 55, and an Al electrode having a thickness of 2 μm is used as the patch electrode 15. A thickness of the liquid crystal layer LC (here, a gap between the patch electrode 15 and the slot electrode 55) is 5 μm, for example. Moreover, a size of each of the antenna units U1 and U2 is 3 mm×4 mm, a size of the slot 57 (width s2×length s1) is 380 μm×3100 μm, and a size of the patch electrode 15 (width p2×length p1) is 318 μm×584 μm. Alternatively, a size of the antenna unit U may be 3 mm×4 mm, the size of the slot 57 (width s2×length s1) may be 458 μm×3300 μm, and the size of the patch electrode 15 (width p2×length p1) may be 508 μm×660 μm. The thickness, size, or the like of each electrode or liquid crystal layer is not limited to the above description, and may be set adequately depending on a frequency of a target microwave or the like.

In the antenna unit U1, the voltage is applied to the liquid crystal layer LC by the solid portion 56 that is the upper electrode UE and the patch electrode 15 that is the lower electrode LE. In a case where the voltage is applied to the liquid crystal layer LC, the liquid crystal molecules, at a portion in the liquid crystal layer LC located between the solid portion 56 and the patch electrode 15, are aligned in the vertical direction (that is, the thickness direction of the liquid crystal layer LC). As described above, the liquid crystal layer LC is covered by the non-transparent upper electrode UE (solid portion 56), this alignment state cannot be observed from an upper side of the slot substrate 201.

In the antenna unit U1, an oblique electric field may also be generated between an edge 56 e of the solid portion 56 and the patch electrode 15. Therefore, a portion in the liquid crystal layer LC located between the edge 56 e of the solid portion 56 and the patch electrode 15 is aligned in parallel with the oblique electric field. In a case where the oblique electric field is large to some degree, the alignment state caused by the oblique electric field (where the liquid crystal molecules are obliquely aligned) can be observed from the slot substrate 201 side.

On the other hand, in the antenna unit U2, no voltage is applied to the liquid crystal layer LC, and the liquid crystal molecules are aligned substantially horizontally between the solid portion 56 and the patch electrode 15. No oblique electric field is generated at a portion in the liquid crystal layer LC between the edge 56 e of the solid portion 56 and the patch electrode 15, and thus the liquid crystal molecules are aligned generally in the horizontal direction (an in-plane direction of the liquid crystal layer).

Herein, a region in each antenna unit where the liquid crystal alignment can be observed from the upper side of the upper electrode UE is called an “observation region Ur”. In alignment inspection I, the observation region Ur is a region where the liquid crystal molecules can be aligned because of the oblique electric field and which is not covered by the upper electrode UE (here, the solid portion 56). In this example, the antenna unit U1 includes two observation regions Ur1 extending in the slot length direction y. The antenna unit U2 also includes two observation regions Ur2 similarly. Each of the observation regions Ur1 and Ur2 is located in the slot 57 and near the edges of the solid portion 56, and is a region overlapping the patch electrode 15.

An intensity of a reflected light from the observation region Ur1 or Ur2 (or, tones of the observation region Ur1 or Ur2) when these antenna units U1 and U2 are magnified and observed under a reflected light microscope makes it possible to distinguish whether the liquid crystal alignment is controlled in the antenna unit. Specifically, as illustrated in FIG. 21B, in the observation region Ur1 in which the liquid crystal molecules are aligned in an oblique direction, the intensity of the reflected light from the observation region Ur1 is relatively high. In other words, the observation region Ur1 is in a “bright (or white)” state. On the other hand, in the observation region Ur2 in which the liquid crystal molecules are aligned in the horizontal direction, the intensity of the reflected light from the observation region Ur2 is relatively low, and the observation region Ur2 is in a “dark (or black)” state. In this way, a state of the liquid crystal alignment in the antenna unit can be seen from the intensity of the reflected light from the observation region Ur (or, the tones of the observation region Ur), which can determine whether the voltage is applied to the liquid crystal layer LC. A possible reason why the liquid crystal alignment causes the intensity of the reflected light to change is that when the liquid crystal alignment varies, the refractive index of the liquid crystal layer changes, and as a result, a reflectivity at an interface between the liquid crystal layer and the lower electrode changes.

The tones of the observation region Ur can be distinguished visually or through image processing. In a case of the image processing, an image acquired in the case that the voltage is not applied or applied to the liquid crystal layer may be used as a reference image to calculate a difference between an image obtained by the alignment inspection and the reference image. A difference value calculated for each antenna unit is compared with a threshold, and the tones of the observation region Ur can be distinguished. Alternatively, as described later, images for a case where the voltage is applied to the gate bus line and the source bus line and for a case where the voltage is not applied to these bus lines may be acquired for each antenna unit to calculate an amount of change in luminance between the observation regions Ur in these images. The amount of change in the luminance calculated for each antenna unit is compared with a threshold, which can distinguish the tones of the observation region Ur.

The observation of the liquid crystal alignment may be performed from the TFT substrate 101 side. FIG. 22A is a cross-sectional view schematically illustrating the alignment state of the antenna unit in the scanning antenna 1000, and FIG. 22B is a plan view exemplarily illustrating a result of observing the alignment state of each antenna unit. This example is the same as the example in FIG. 21A and FIG. 21B except that the liquid crystal alignment is observed from the TFT substrate 101 side.

In the example illustrated in FIG. 22A and FIG. 22B, the patch electrode 15 is an upper electrode UE, and the solid portion 56 is a lower electrode LE. The observation is made from the TFT substrate 101 side on a change in the liquid crystal alignment caused by the oblique electric field generated between an edge 15 e of the patch electrode 15 that is the upper electrode UE and the solid portion 56 that is the lower electrode LE. In this case, each of the observation regions Ur1 and Ur2 in the respective antenna units U1 and U2, when viewed from the normal direction of the TFT substrate 101, is a portion on the solid portion 56 not covered by the patch electrode 15 and is a region located near the edge 15 e of the patch electrode 15.

When the antenna units U1 and U2 are observed under a reflected light microscope, as illustrated in FIG. 22B, the observation region Ur1 in the antenna unit U1 where the voltage is applied to the liquid crystal layer LC is in the “bright” state, and the observation region Ur2 in the antenna unit U2 where the voltage is not applied to the liquid crystal layer LC is in the “dark” state.

Shape of Patch Electrode 15 and Slot Electrode 55

In alignment inspection I according to the present embodiment, a change in the liquid crystal alignment caused by the oblique electric field can easily observed by increasing the oblique electric field, or enlarging the observation region Ur or the region where the oblique electric field is generated.

Hereinafter, a description is given of a shape of the electrode that allows the liquid crystal alignment to be easily observed by use of the oblique electric field, with reference to the drawings.

As described above with reference to FIG. 21A and FIG. 21B and FIG. 22A and FIG. 22B, in alignment inspection, the liquid crystal alignment is observed that is caused by the oblique electric field generated between an edge UEe of the upper electrode UE and the lower electrode LE. At this time, the thicker the upper electrode UE, the larger an area of a side surface of the upper electrode UE which can generate the oblique electric field with the lower electrode LE, and thus the thick upper electrode UE can increase the oblique electric field. A thickness D1 of the upper electrode UE is preferably 2 μm or greater, for example. This increases the oblique electric field, and the increased oblique electric field produces a great change in the liquid crystal alignment. Therefore, the difference in the intensity of the reflected light depending on the presence or absence of the oblique electric field is increased, which allows the tones to be distinguished more easily.

The upper electrode UE and/or the lower electrode LE may have a planar shape that allows an area of the observation region Ur in each antenna unit U to increase. Enlargement of the size of the observation region Ur allows a magnification and resolution required for the inspection device to be kept low. For example, when viewed from the normal direction of the TFT substrate or slot substrate (hereinafter, referred to as a “substrate normal direction” or a “normal direction of the first dielectric substrate” in some cases), a periphery of the upper electrode UE and/or the lower electrode LE may have steps (a recessed portion or a protruding portion).

As an example, in a case where the solid portion 56 is the upper electrode UE, when viewed from the substrate normal direction, the periphery of the solid portion 56 may have a recessed portion (a first recessed portion) in the portion overlapping the patch electrode 15. In a case where the patch electrode 15 is the upper electrode UE, when viewed from the substrate normal direction, the periphery of the patch electrode 15 may have a recessed portion (a second recessed portion) in the portion overlapping the solid portion 56.

FIG. 23A is a plan view exemplarily illustrating the electrode shape of the present embodiment, and FIG. 23B is an enlarged view of a part of FIG. 23A. FIG. 23C is a plan view exemplarily illustrating another electrode shape.

As illustrated in FIG. 23A and FIG. 23B, when viewed from the substrate normal direction, a portion of the edge UEe of the upper electrode UE (here, the solid portion 56) overlapping the lower electrode LE (here, the patch electrode 15,) may have a slit (a first recessed portion) 81. This can increase a length of the portion of the edge UEe of the upper electrode UE overlapping the lower electrode LE, increase the region where the oblique electric field can be generated in the liquid crystal layer LC, and also increase the size of the observation region Ur. Here, the solid portion 56 has the rectangular periphery, and the recessed portions 81 are formed in two sides of the periphery across the patch electrode 15, but the recessed portion 81 may be formed only in one side.

A size of the slit 81 is not specifically limited to a specific size. In this example, from the viewpoint that an influence on the antenna performance due to the formation of the slit 81 is suppressed, a width 81 w of the slit 81 may be 50% or less of the width p2 of the patch electrode 15 in the slot length direction y, and a depth 81 d of the slit 81 may be 5% or less of the width s2 of the slot 57. Meanwhile, the width 81 w of the slit 81 is preferably 10% or greater of the width p2 of the patch electrode 15, and the depth 81 d of the slit 81 is preferably 1% or greater of the width s2 of the slot 57. This makes it possible to more efficiently enlarge the observation region Ur.

The same holds for the case that the patch electrode 15 is the upper electrode UE. For example, as illustrated in FIG. 23C, a slit (a second recessed portion) 82 may be provided in a portion of the edge 15 e of the patch electrode 15 overlapping the solid portion 56. This makes it possible to enlarge the observation region Ur. Here, the patch electrode 15 has the rectangular periphery, and the recessed portions 82 are formed in two sides extending in the slot length direction y, but the recessed portion 82 may be formed only in one side.

The electrode shape in the present embodiment is not limited to the examples in FIG. 23A to FIG. 23C. For example, a protruding portion may be provided in the periphery of the patch electrode 15 to partially increase the width of the patch electrode 15 (the width in the slot length direction y) when viewed from the substrate normal direction. As an example, the protruding portion may be disposed such that the width of the patch electrode 15 on at least one of ends of the patch electrode 15 is larger than the rest.

FIG. 24A is a plan view exemplarily illustrating another electrode shape of the present embodiment, and FIG. 24B is an enlarged view of a part of FIG. 24A. FIG. 24C is a plan view exemplarily illustrating another electrode shape.

As illustrated in FIG. 24A and FIG. 24B, in a case where the solid portion 56 of the slot electrode 55 is the upper electrode UE, the patch electrode 15 may have a shape in which its width near the edge of the upper electrode UE is larger than the other portion. Specifically, a portion of the periphery of the patch electrode 15 extending in the slot width direction x includes a protruding portion (a first protruding portion) 83. The protruding portion 83 is located near the edge 56 e of the solid portion 56. This brings a portion of the patch electrode 15 located near the edge 56 e of the solid portion 56 in the slot 57 to have a greater width (maximum width) p3 than the width p2 of the other portion. This allows a length of a portion of the edge of the solid portion 56 overlapping the patch electrode 15 to be increased when viewed from the substrate normal direction, and therefore, the size of the observation region Ur can be increased. In other words, the length of the observation region Ur in the second direction increases by a height of the protruding portion 83 (or, is equal to the width p3 of the patch electrode 15).

From the viewpoint that an influence on the antenna performance due to the partially increased width of the patch electrode 15 is suppressed, the maximum width p3 of the patch electrode 15 (the width near the edge UEe) may be 150% or less of the width p2 of the other portion, and a length s3, in the width direction of the slot 57, of a portion having the width p3 in the slot 57 may be 5% or less of the width s2 of the slot 57. On the other hand, in a case where the maximum width p3 of the patch electrode 15 is 110% or greater of the width p2 of the other portion and the length s3 is 1% or greater of the width s2 of the slot 57, the observation region Ur can be more efficiently enlarged.

In the case where the patch electrode 15 is the upper electrode UE, as illustrated in FIG. 24C, for example, a portion of the periphery of the patch electrode 15 extending in the slot width direction x may have the protruding portion (first protruding portion) 83 such that the width of the patch electrode 15 is larger at a portion overlapping the solid portion 56 than the other portion. This can increase a length of a portion of the edge 15 e of the patch electrode 15 overlapping the solid portion 56 when viewed from the substrate normal direction, and therefore, the size of the observation region Ur can be increased. In other words, the length of the observation region Ur in the slot length direction y is equal to the maximum width p3 of the patch electrode 15.

The slits 81 and 82 are disposed on both sides of the slot 57 in FIG. 23A and FIG. 23C, but may be disposed only on one side. Protrusions (protruding portions) may be disposed in place of the slits 81 and 82. The width of the patch electrode 15 is increased on both ends thereof in FIG. 24A and FIG. 24C, but may only be increased on one end more than the width of the other end. The ends of the patch electrode 15 are provided with, in the plan views illustrated in FIG. 24A to FIG. 24C, the protruding portion extending from an upper side of the patch electrode 15 and the protruding portion extending from a lower side which are opposite to each other, but any one of the protruding portions may only be provided. Furthermore, the electrode according to the present embodiment may have two or more of the first recessed portion, the second recessed portion, and the first protruding portion described using FIG. 23A to FIG. 23C and FIG. 24A to FIG. 24C. For example, the slot electrode 55 may have the slit 81, and the patch electrode 15 may have the protruding portion 83.

The electrode shapes illustrated in FIG. 23A to FIG. 23C and FIG. 24A to FIG. 24C may be applied to all the antenna units U constituting the scanning antenna, or only to some of the antenna units U which may be the inspection targets. Applying selectively to some of the antenna units U can further reduce the influence on the antenna performance.

Alignment Inspection II

In alignment inspection II, a transparent electrode (hereinafter, referred to as an “inspection transparent electrode”) is provided in contact with one of the patch electrode and the slot electrode, which is an electrode located on the observer side (upper electrode), to observe the liquid crystal alignment.

FIG. 25A and FIG. 25B are a schematic cross-sectional view of the scanning antenna not including the inspection transparent electrode and a schematic top view illustrating a result of observing the liquid crystal alignment of the antenna unit, respectively. FIG. 26A and FIG. 26B are a schematic cross-sectional view and a schematic top view of a scanning antenna 1000A provided with the inspection transparent electrodes, respectively. FIG. 26C is a schematic top view illustrating a result of observing the liquid crystal alignment of the antenna unit.

FIG. 25A and FIG. 25B and FIG. 26A to FIG. 26C illustrate examples in which the observation is made from the slot substrate 201 side. The drawings exemplarily illustrate two antenna units U1 and U2 of a plurality of antenna units. The antenna unit U1 is illustrated as an example in which the voltage is applied to the liquid crystal layer LC and the liquid crystal molecules are favorably aligned in the vertical direction (the thickness direction of the liquid crystal layer LC), and the antenna unit U2 is illustrated as an example in which no voltage is applied to the liquid crystal layer LC from any cause and the liquid crystal molecules are aligned in the horizontal direction (the in-plane direction of the liquid crystal layer LC) (alignment failure).

As can be seen from FIG. 25A and FIG. 25B, since both the patch electrode 15 and the slot electrode 55 are the metal electrodes, an alignment state of a portion in the liquid crystal layer located between these electrodes cannot be observed from the TFT substrate 101 side or the slot substrate 201 side. Therefore, for example, in a case where a change in the liquid crystal alignment caused by the oblique electric field is small, it is difficult to determine whether the voltage is being applied to the liquid crystal layer.

In contrast, as illustrated in FIG. 26A and FIG. 26B, in the scanning antenna 1000A, a substrate on the observing side (here, the slot substrate 201) is provided with an inspection transparent electrode 92 in contact with the upper electrode UE (here, the solid portion 56 of the slot electrode 55), and the inspection transparent electrode 92 is thinner than the upper electrode UE.

In the scanning antenna 1000A, the voltage is applied to the liquid crystal layer LC by the upper electrode UE and the lower electrode LE so that an alignment state of a portion in the liquid crystal layer LC interposed between the inspection transparent electrode 92 and upper electrode UE and the lower electrode LE can be controlled. In this portion, the liquid crystal alignment of a portion located between the inspection transparent electrode 92 and the lower electrode LE (here, the patch electrode 15) can be observed through the inspection transparent electrode 92 for each antenna unit U.

In the example illustrated in the drawings, the inspection transparent electrode 92 is disposed on the slot substrate 201 while in contact with the solid portion 56 of the slot electrode 55. The inspection transparent electrode 92 is disposed while protruding from the edge of the solid portion 56 toward an inside of the slot 57 when viewed from the substrate normal direction. The inspection transparent electrode 92 includes a region which does not overlap the upper electrode UE (here, the solid portion 56) and overlaps the lower electrode LE (here, the patch electrode 15) (also referred to as an alignment controlled region) when viewed from the substrate normal direction. A region, in the antenna unit U, defined by the alignment controlled region of the inspection transparent electrode 92 is the observation region Ur where the liquid crystal alignment can be observed.

In the alignment inspection, DC driving or low frequency driving (e.g., about 60 Hz) of the scanning antenna 1000A is performed. This allows the liquid crystal alignment to be controlled even with the inspection transparent electrode 92 having relatively high resistance. In a case where the scanning antenna 1000A is driven, in the antenna unit U1, the voltage is applied to the liquid crystal layer LC, and the liquid crystal molecules between the solid portion 56 and inspection transparent electrode 92 and the patch electrode 15 are aligned in the vertical direction (the thickness direction of the liquid crystal layer LC). On the other hand, in the antenna unit U2, no voltage is applied to the liquid crystal layer LC, and the liquid crystal molecules between the solid portion 56 and inspection transparent electrode 92 and the patch electrode 15 are not aligned in a predetermined alignment direction. When these antenna units U1 and U2 are observed under a reflected light microscope similarly to a case in the alignment inspection I, the antenna unit U1, in which the intensity of the reflected light from the observation region Ur1 is relatively high, is in the “bright” state as illustrated in FIG. 26C. The antenna unit U2, in which the intensity of the reflected light from the observation region Ur2 is low, is in the “dark” state. In this way, observing the liquid crystal alignment through the inspection transparent electrode 92 makes it possible to confirm whether the alignment control can be made.

As described later, in the case of the observation from the TFT substrate 101 side, the inspection transparent electrode 92 is disposed to the TFT substrate 101 while in contact with the patch electrode 15. The inspection transparent electrode 92 may extend from the edge of the patch electrode 15 to overlap the solid portion 56 when viewed from the substrate normal direction. The inspection transparent electrode 92 includes the alignment controlled region which does not overlap the patch electrode 15 and overlaps the solid portion 56 when viewed from the substrate normal direction. A region, in the antenna unit U, defined by the alignment controlled region of the inspection transparent electrode 92 is the observation region Ur where the liquid crystal alignment can be observed.

A thickness of the inspection transparent electrode 92 is preferably less than the skin depth. This allows the microwaves to be transmitted and/or received to pass through the inspection transparent electrode 92, and therefore, the decrease in the antenna performance caused by providing the inspection transparent electrode 92 can be suppressed. The thickness of the inspection transparent electrode 92 may be 100 nm or less, for example.

The inspection transparent electrode 92 preferably has an electric resistance greater than that of the upper electrode UE. More preferably, the electric resistance of the inspection transparent electrode 92 is sufficiently greater than that of the upper electrode. For example, in a case where a low resistance metal such as aluminum (an electric resistance: 2.65×10⁻⁸ Ωm), copper (an electric resistance: 1.68×10⁻⁸ Ωm), and silver (an electric resistance: 1.59×10⁻⁸ Ωm) is used as the upper electrode UE, the electric resistance of the inspection transparent electrode 92 may be 10⁻¹ Ωm.

A size of the inspection transparent electrode 92 is not specifically limited to a specific size. In a case where the inspection transparent electrode 92 is provided on the slot substrate 201, a length 92 y of a portion of the inspection transparent electrode 92 not overlapping the solid portion 56 (a portion located in the slot 57) in the slot length direction y may be greater than 0% and less than or equal to 100% of the width P2 of the patch electrode. A length 92 x of the portion described above of the inspection transparent electrode 92 in the slot width direction x may be greater than 0% and less than or equal to 50% of the width s2 of the slot 57.

Examples of material of the inspection transparent electrode 92 are not limited to a specific material, but may include metal oxide such as ITO and In—Ga—Zn—O. Alternatively, Si based semiconductor such as amorphous silicon may be used. The inspection transparent electrode 92 needs only have a visible light transmittance to a degree that the liquid crystal alignment can be observed, and a metal thin film may be used. A semiconductor film which is the same as an active layer of the TFT on the TFT substrate (e.g., In—Ga—Zn—O based metal oxide film) may be used to form the inspection transparent electrode 92. A conductive film for a terminal of the TFT substrate or the slot substrate (e.g., an ITO film) may be used to form the inspection transparent electrode 92.

As can be seen from FIG. 25A to FIG. 25B and FIG. 26A to FIG. 26C, even in a case where the inspection transparent electrode 92 is provided, a degree of change in the dielectric constant of the liquid crystal layer LC does not change at an intersected portion of the solid portion 56 and the patch electrode 15 in the liquid crystal layer LC (hereinafter, referred to as a slot portion). The pitch of the antenna unit U also does not change by disposing the inspection transparent electrode 92. Furthermore, the scanning antenna 1000 is driven at a high frequency. Therefore, it can be considered that even in a case where the inspection transparent electrode 92 is disposed, the antenna performance suffers little influence.

The disposition of the inspection transparent electrode 92 is not limited to the example illustrated in FIG. 26A to FIG. 26C. To electrically connect the inspection transparent electrode 92 to the solid portion 56, the inspection transparent electrode 92 may be connected to at least part of the surfaces (side surface and upper face) of the solid portion 56. For example, as illustrated in FIG. 27, the inspection transparent electrode 92 may cover the entirety of a portion of the solid portion 56 located between two adjacent slots 57. In a case where the inspection transparent electrode 92 is in contact with not only the side surface of the solid portion 56 but also the side surface and the upper face, a contact resistance of the inspection transparent electrode 92 and the solid portion 56 can be reduced. Moreover, the inspection transparent electrode 92 can be prevented from peeling off.

In the examples illustrated in FIG. 26A to FIG. 26C and FIG. 27, the inspection transparent electrode 92 is disposed to each of the right and left edges of one slot 57, that is, two inspection transparent electrodes 92 are provided to one antenna unit. In contrast, one inspection transparent electrode 92 may be provided to one antenna unit U.

FIG. 28A and FIG. 28B are a cross-sectional view and a top view illustrating another disposition example of the inspection transparent electrode 92, respectively. FIG. 28C is a top view illustrating a result of observing the liquid crystal alignment.

In a scanning antenna 1000B illustrated in FIG. 28A to FIG. 28C, the inspection transparent electrode 92 is disposed only to the edge on one side of the slot 57 (here, right side). One inspection transparent electrode 92 is disposed to one antenna unit U. Other configurations are the same as the configuration illustrated in FIG. 26A to FIG. 26C. In the scanning antenna 1000B, the influence on the antenna operation owing to disposition of the inspection transparent electrode 92 can be further reduced as compared with the scanning antenna 1000A exemplarily illustrated in FIG. 26A to FIG. 26C and FIG. 27, for example.

FIG. 26A to FIG. 28C illustrate the examples in which the inspection transparent electrode 92 is provided on the slot substrate 201, but as described above, the inspection transparent electrode 92 may be provided on the TFT substrate 101 to observe the liquid crystal alignment from the TFT substrate 101 side.

FIG. 29A and FIG. 29B are a cross-sectional view and a top view illustrating yet another disposition example of the inspection transparent electrode 92, respectively. FIG. 29C is a top view illustrating an observation result.

In a scanning antenna 1000C illustrated in FIG. 29A to FIG. 29C, the liquid crystal alignment is observed from the TFT substrate 101 side. Therefore, the patch electrode 15 is the upper electrode UE, and the solid portion 56 of the slot electrode 55 is the lower electrode LE. The inspection transparent electrode 92 is disposed in contact with the patch electrode 15 and extends to overlap the solid portion 56 with the liquid crystal layer LC interposed therebetween.

The inspection transparent electrode 92 preferably extends in the slot length direction y from a portion of the periphery of patch electrode 15 extending in the slot width direction x so that the length p1 (the length in the slot width direction x) of the patch electrode 15 is not affected. This can reduce the influence on the antenna performance.

In the scanning antenna 1000C, the inspection transparent electrode 92 also includes a region (alignment controlled region) which does not overlap the patch electrode 15 but overlaps the solid portion 56 when viewed from the substrate normal direction. A region, in the antenna unit U, defined by the alignment controlled region is the observation region Ur. The inspection transparent electrode 92 is preferably disposed not to overlap the slot 57. When the liquid crystal alignment is observed from the upper side of the TFT substrate 101, as illustrated in FIG. 29C, the observation region Ur1 is in the “bright” state in the antenna unit U1 where the voltage is applied to the liquid crystal layer LC, and the observation region Ur2 is in the “dark” state in the antenna unit U2 where the voltage is not applied to the liquid crystal layer LC.

As is in this example, in a case where the inspection transparent electrode 92 is provided to the TFT substrate 101, the length 92 y of the portion of the inspection transparent electrode 92 not overlapping the patch electrode 15 in the slot length direction y may be greater than 0% and less than or equal to 30% of the length s1 of the slot 57. The length 92 x of the portion described above of the inspection transparent electrode 92 in the slot width direction x may be greater than 0% and less than or equal to 30% of the width of the solid portion 56 (that is, a distance between two adjacent slots 57).

FIG. 30A and FIG. 30B are cross-sectional views illustrating yet another disposition example of the inspection transparent electrode 92, and FIG. 30C is a plan view illustrating another disposition example. FIG. 30A and FIG. 30B illustrate the cross-section views along a line B-B and a line C-C in FIG. 30C, respectively. FIG. 30D is a top view illustrating a result of observing the liquid crystal alignment.

In a scanning antenna 1000D illustrated in FIG. 30A to FIG. 30D, the inspection transparent electrode 92 is disposed to each of two sides of the periphery of the patch electrode 15 extending in the slot width direction x. In this example, the inspection transparent electrode 92 also extends from the edge of the patch electrode 15 in the slot length direction y. However, the length of the inspection transparent electrode 92 in the slot width direction x is shorter than that in the example illustrated in FIG. 29A to FIG. 29C. For this reason, substantially the entire of the inspection transparent electrode 92 is located between a straight line 94 including the side of the patch electrode 15 extending in the slot length direction y and the slot 57. Therefore, the influence of the inspection transparent electrode 92 on the length p of the patch electrode 15 in the slot width direction x can be further suppressed, and thus the influence on the antenna performance can be further reduced.

In the examples illustrated in FIG. 29A to FIG. 29C and FIG. 30A to FIG. 30D, the inspection transparent electrode 92 is in contact with a lower face of the patch electrode 15, but may be in contact with a side surface or upper face of the patch electrode 15.

FIG. 31 is a schematic cross-sectional view exemplarily illustrating a more specific configuration of the slot substrate 201 in which the inspection transparent electrode 92 is disposed. In this example, a transparent conductive film (ITO film) for a terminal is used to form the upper connection section 60 and the inspection transparent electrode 92. The slot substrate 201 of this example has the same configuration as that of the slot substrate 201 illustrated in FIG. 6 except that the slot substrate 201 of this example includes the inspection transparent electrode 92, and a detailed description thereof is omitted.

FIG. 32 is a schematic cross-sectional view exemplarily illustrating a more specific configuration of the TFT substrate 101 in which the inspection transparent electrode 92 is disposed. In this example, a transparent conductive film for a terminal is used to form the source terminal upper connection section 19 s, the gate terminal upper connection section 19 g, and the inspection transparent electrode 92. The TFT substrate 101 of this example has the same configuration as that of the TFT substrate 101 illustrated in FIG. 3A and FIG. 3B except that the TFT substrate 101 of this example includes the inspection transparent electrode 92, and a detailed description thereof is omitted. Although not illustrated in the drawing, a common oxide semiconductor film may be used to form the active layer of the TFT 10 and the inspection transparent electrode 92.

Configuration of Inspection Device Used in Alignment Inspection

Next, a description is given of an inspection device which can be used in the alignment inspections I and II. The same inspection device equipped with a reflected light microscope can be used in the alignment inspections I and II.

FIG. 33 is a schematic perspective view of an inspection device 401 used for the alignment inspections.

The inspection device 401 includes a stage 181 on which the scanning antenna 1000 is placed, a probing jig 189 configured to connect the scanning antenna 1000 on the stage 181 to the power source, a microscope 183 under which a predetermined region of the scanning antenna 1000 on the stage 181 are enlarged and observed. The stage 181 is a movable stage and movable in two directions in a plane (an X direction and a Y direction perpendicular to the X direction) relative to the microscope 183. Instead, a head of the microscope 183 may be a movable head and movable in the X direction and in the Y direction relative to the stage 181.

The scanning antenna 1000 includes the transmission and/or reception region R1 including a plurality of antenna units U, and the non-transmission and/or reception region R2 located around the region R1. The non-transmission and/or reception region R2 is provided with a maker 190 that is a reference position mark.

The stage 181 or the head of the microscope 183 is moved to allow an antenna unit positioned at specified coordinates to be disposed on an observation position of the microscope 183 on the basis of the reference position mark provided to the scanning antenna 1000.

FIG. 34 is a schematic perspective view of another inspection device 402.

The inspection device 402 includes the microscope (a coaxial white visible light microscope) 183 provided with a camera system 185. Therefore, the alignment inspections can be automatically performed by the image processing. A guide pin 187 configured to hold the scanning antenna 1000 at a predetermined position may be provided on the stage 181. Although not illustrated in the drawing, the inspection device 402 may further include a loader/unloader configured to mount/remove the scanning antenna 1000 as the inspection target on and from the inspection device 402. Other configurations are the same as that of the inspection device 401.

Configuration of Reference Position Mark

In the alignment inspections, a position of the antenna unit that is to be the inspection target is preferably managed by the coordinates. The coordinates may be defined on the basis of the reference position mark provided to the non-transmission and/or reception region of scanning antenna 1000.

FIG. 35A and FIG. 35B are a plan view exemplarily illustrating the reference position marks of the scanning antenna 1000 and an enlarged top view of the marker, respectively. The scanning antenna 1000 includes the transmission and/or reception region R1 including a plurality of antenna units U, and the non-transmission and/or reception region R2 located around the region R1. The non-transmission and/or reception region R2 is provided with a plurality of makers 190A to 190C as the reference position marks. In this example, the makers 190A to 190C are arranged at separate corners of the non-transmission and/or reception region R2. A straight line 191 passing through the makers 190A and 190B is parallel to a long side of an outline of the scanning antenna 1000, and a straight line 192 passing through the makers 190A and 190C is parallel to a short side of the outline of the scanning antenna 1000. Assuming that the center of the maker 190A is an origin, the straight line 191 is an X-axis, and the straight line 192 is a Y-axis, the antenna unit U in the transmission and/or reception region R1 can be expressed by the coordinates.

The makers 190A to 190C may have a cross pattern as illustrated in FIG. 35B, for example. In this example, each of two lines intersecting in the cross pattern has a width m1 of 100 μm and a length m2 of 400 μm. The makers 190A to 190C may be formed using the same conductive film as that of a gate wiring line in the TFT substrate, for example.

Process Flow of Alignment Inspections

Next, a description is given of process flows of the alignment inspections I and II.

In performing the alignment inspections, first, the antenna unit that is to be the inspection target is selected in advance from a plurality of antenna units constituting the scanning antenna. Herein, the antenna unit (typically, the plurality of antenna units) selected as the inspection target is called a “basic inspection element”. For example, a plurality of antenna units may be divided into a plurality of groups depending on the source bus lines or gate bus lines to which the antenna units are connected, and one or more antenna units may be selected as the basic inspection elements for each group in advance. This makes it possible to efficiently detect a malfunction which may occur for each group such as the short circuit or disconnection of the wiring line. All the antenna units constituting the scanning antenna may be the inspection targets.

In the alignment inspections, first, one of a plurality of basic inspection elements (called an “inspection target element”) is positioned on the observation position of the microscope 183 to observe the liquid crystal alignment. Next, one of the rest of the basic inspection elements is positioned on the observation position of the microscope 183 to observe the liquid crystal alignment in the same manner as the first one. In this way, the liquid crystal alignments of a plurality of basic inspection elements are sequentially observed. After that, a failure ratio of the antenna units is calculated on the basis of the observation result.

With reference to FIG. 36, a description is given of an example of a process flow of the alignment inspection method I using the inspection device 402 (FIG. 34).

First, a scanning antenna that is to be the inspection target (hereinafter, referred to as a “panel”) is placed on the stage 181 (step S1). The panel may be placed manually, or by use of the loader (not illustrated). Next, the position of the panel is determined along the guide pin 187 on the stage 181 (step S2). Subsequently, the source bus line and the gate bus line of the panel are connected to the power source using the probing jig 189 (step S3).

Next, the position of the panel is confirmed using the makers provided to the panel (FIG. 35A and FIG. 35B)(step S4). After that, one of the basic inspection elements is selected as the inspection target element, the panel is moved relative to the microscope 183 on the basis of coordinates corresponding to the inspection target element (inspection element coordinates), and the inspection target element is positioned on a position at which the observation by the microscope 183 is made (step S5).

Subsequently, a voltage is applied to the source bus line. Here, a voltage of about from +2 to 10 V is applied to the source bus line, for example. The slot electrode is connected to a reference potential (ground). In this state, a change in the liquid crystal alignment before and after a gate voltage is applied is observed (step S6). Here, +18 V is applied to the gate bus line when the gate voltage is applied, for example.

The observation of the liquid crystal alignment is made as below, for example. First, a light source such as a white visible light source and a white LD (laser diode) is used to adjust an amount of visible light with which the inspection target element is irradiated. Subsequently, the visible light is made incident on the inspection target element, and the intensity of the reflected light from the observation region Ur (region where the liquid crystal alignment can be observed) is measured. A preset reference intensity of the reflected light is compared with the measured intensity of the reflected light to determine whether the liquid crystal molecules are aligned in a predetermined direction by the oblique electric field. Specifically, in a case where the intensity of the reflected light is greater than or equal to the reference intensity (in the “bright” state), it is determined that the oblique electric field is generated, that is, a predetermined voltage is applied to the liquid crystal layer in the inspection target element. On the other hand, in a case where the intensity of the reflected light is less than the reference intensity (in the “dark” state), it is determined that the oblique electric field is not generated, that is, a predetermined voltage is not applied to the liquid crystal layer in the inspection target element, and the liquid crystal molecules do not have a predetermined alignment (alignment failure). Possible factor of the “alignment failure” is that some kind of failure of the wiring line or a failure of the inspection target element itself (single element failure) occurs.

Instead of the measurement of the reflected light, the “bright” state or the “dark” state may be distinguished visually or through the image processing. Alternatively, an automatic inspection can also be performed. In the automatic inspection, a process described below may be performed at step S6, for example. First, images of the inspection target element before and after the gate voltage is applied are acquired. Next, these images are compared, and an amount of change in the luminance at a point where the amount of change is maximum is measured to determine the presence or absence of the alignment failure on the basis of a preset reference value of the amount of change in the luminance. For example, in a case where the measured amount of change in the luminance is less than the preset reference value, it is determined that the alignment failure occurs in the inspection target element.

Subsequently, one of the basic inspection elements of which the alignment states are still not observed is selected as a new inspection target element, and steps S5 to S6 are similarly performed to observe the liquid crystal alignment. In this way, the liquid crystal alignments of all the basic inspection elements are sequentially observed.

After that, on the basis of the observation results, a ratio of the antenna units having the alignment failures (element failure ratio), or a ratio of line defects (wiring line disconnection or the like) or the like is calculated to determine the presence or absence of the malfunction (panel failure) for the entire panel.

Note that in a case where the inspection target element is determined to have an alignment failure, in order to investigate a factor of the alignment failure, the antenna unit other than the basic inspection element may be selected as an additional inspection element to observe the liquid crystal alignment of the additional inspection element.

FIG. 37 is a diagram illustrating another process flow of the alignment inspection I. Steps S1 to S6 are the same as the steps described above with reference to FIG. 36.

In this example, in a case where as a result of observing the liquid crystal alignment at step S6, the inspection target element is determined not to have a predetermined liquid crystal alignment, a further inspection is performed to investigate the factor of the failure (step S7).

For example, the liquid crystal alignments of another antenna unit Ug connected to the gate bus line common to the inspection target element which is determined to have the alignment failure (called an “alignment failure element”) and another antenna unit Us connected to the source bus line common to the alignment failure element are observed in the same way as in steps S5 to S6. This makes it possible to determine whether the short circuit, disconnection, or the like occurs in the source bus line or the gate bus line (line failure), or failure of a single element (single element failure) occurs. Specifically, in a case where the alignment failure occurs in the antenna unit Ug, it is determined that the disconnection or the like occurs in the gate bus line, and in a case where the alignment failure occurs in the antenna unit Us, it is determined that the disconnection or the like occurs in the source bus line. In a case where both the antenna units Ug and Us have predetermined liquid crystal alignments, the failure is determined to be the “single element failure”, that is, the alignment failure element itself has a failure.

After that, the next basic inspection element is selected as an inspection target element to observe the liquid crystal alignment along steps S5 to S6. In a case where the inspection target element is determined to have the alignment failure, a step S7 is performed to identify the factor of the alignment failure. In this way, other basic inspection elements are sequentially subjected to alignment inspection in the same way to investigate the factor of the alignment failure.

Subsequently, on the basis of the observation result, the single element failure ratio and the number of line defects of the panel are found. The single element failure ratio is a ratio of the number of elements determined to have the single element failure to the total number of basic inspection elements.

After that, the calculated single element failure ratio and the calculated number of line defects are compared with preset upper limits of the single element failure ratio and the number of line defects to determine the presence or absence of the malfunction (panel failure) for the entire panel. The preset upper limit of the single element failure ratio may be 10%, and the upper limit of a line defect ratio (a ratio of the number of line defects to the total number of lines) may be 1%, for example.

Alternatively, the “element failure ratio” may be calculated from the single element failure ratio and the number of line defects calculated from the observation result. Here, the failure ratio owing to the line defect is calculated assuming that malfunctions occur in all antenna units connected to that line. A total failure ratio of the failure ratio owing to the line defect and the single element failure ratio is defined as the “element failure ratio”. The calculated element failure ratio may be compared with the preset upper limit of the element failure ratio to determine the presence or absence of the panel failure. The preset upper limit of the element failure ratio may be 10%, for example.

According to the inspection method illustrated in FIG. 37, even in a case where all the antenna units U are not inspected, not only the presence or absence of the panel malfunction but also the factor of the malfunction can be investigated. Therefore, it is possible to more efficiently and reliably perform the alignment inspection.

Note that although the process flow of the alignment inspection I is exemplarily illustrated in FIG. 36 and FIG. 37, the same process flow can also be applied to a case where the inspection transparent electrode is used to observe the liquid crystal alignment (in alignment inspection II). The voltage for driving the panel in the alignment inspections may be or may not be the same between the alignment inspection I and the alignment inspection II. When the liquid crystal alignment is observed in the alignment inspection II, a voltage of +2 to 10 V is applied to the source bus line, a voltage of +18 V is applied to the gate bus line, and a voltage of 0 V is applied to the slot electrode, for example.

Selection Method of Basic Inspection Element

In the alignment inspections exemplified in FIG. 36 and FIG. 37, inspecting the liquid crystal alignments of only some of a plurality of antenna units constituting the scanning antenna allows an inspection time and inspection cost to be suppressed to improve throughput. Hereinafter, a description is given of an example of a method for selecting the antenna unit (basic inspection element) that is to be the inspection target.

FIG. 38 is a schematic diagram illustrating a part of the antenna unit U in the scanning antenna 1000.

First, in a plurality of antenna units, a plurality of antenna units connected to the same wiring line (here, source bus line S) are assumed to be one group and grouped.

In this example, a plurality of source bus lines S(1) to S(3) extend in a row direction. Each of the source bus lines is connected to the patch electrodes 15 of a plurality of antenna units with the TFTs (not illustrated) therebetween.

The source bus line S(1) is connected with the patch electrodes 15 of a plurality of antenna units U(1 a) to U(1 g) arranged in the row direction. These antenna units U(1 a) to U(1 g) are defined as a group 1. Similarly, a plurality of antenna units U(2 a) to U(2 g) of which the patch electrodes 15 are connected to the source bus line S(2) are defined as a group 2, and a plurality of antenna units U(3 a) to U(3 g) of which the patch electrodes 15 are connected to the source bus line S(3) is defined as a group 3.

Next, the inspection target elements are configured for each group. For example, the antenna units U(1 a), (1 d), and (1 g), and the antenna units belong to the same column as those may be selected as the basic inspection elements. The number of basic inspection elements, an array thereof, and the like are not limited to the example illustrated in the drawing.

Two or more basic inspection elements are preferably selected for each group. In a case where the alignment failures occur in all the basic inspection elements in a certain group, it can be determined that a failure such as the short circuit, disconnection or the like occur in the wiring lines connected to the antenna units in that group. Therefore, all the antenna units in that group are considered to have the malfunction (group failure).

FIG. 39 is a diagram for illustrating another method for selecting an inspection target element according to the present embodiment, and illustrates a part of the antenna units U of the TFT substrate in the scanning antenna 1000.

A plurality of source bus lines S(1) to S(3) extend in row direction, and a plurality of gate bus lines G(1) to G(3) extend in the column direction. A plurality of antenna units are arranged in the row direction and the column direction. The gate electrodes of the TFTs of the antenna units in the same column are connected to the same gate bus line, and the source electrodes of the TFTs of the antenna units in the same row are connected to the same source bus line. Here, assume that an antenna unit including a TFT connected to a source bus line S(n) and a gate bus line G(m) is expressed by U(n-m). For example, a TFT of an antenna unit (1-1) is connected to the source bus line S(1) and the gate bus line G(1).

In this example, the antenna units U(1-1), U(2-2), and U(3-3) are defined as the basic inspection elements. These antenna units are not connected to the wiring line (the gate bus line and the source bus line) common to each other. In a case that the liquid crystal alignment of a certain basic inspection element is determined to be normal, it is determined that a failure does not occur in the source bus line and gate bus line connected to that basic inspection element. According to this method, the number of basic inspection elements required for investigating all the line failures can be reduced, allowing the inspection cost and the inspection time to be further reduced.

In a case where it is determined that the alignment failure occurs in a certain basic inspection element, the step S7 described above with reference to FIG. 37 may be performed, for example. In other words, the alignment inspection may be performed on other antenna units connected to the common wiring line to determine whether the short circuit or the like occurs in the source bus line or the gate bus line (line failure), or whether the single element failure occurs. For example, in a case where the antenna unit U(2-2) is determined to have the alignment failure, the liquid crystal alignments of other antenna units U(1-2), U(3-2) and the like connected to the gate bus line common to the antenna unit U(2-2) are inspected. Similarly, the liquid crystal alignments of other antenna units U(2-1), U(2-3), and the like connected to the source bus line common to the antenna unit U(2-2) are inspected. This makes it possible to determine the presence or absence of the gate bus line failure or source bus line failure. In a case where any line failure does not occur, it is determined that the antenna unit U(2-2) itself has a failure (single element failure).

Structure of Basic Inspection Element

To easily observe the liquid crystal alignment in the observation region of the basic inspection element, an electrode structure of the basic inspection element may be differentiated from electrode structures of other antenna units. For example, at least one of the upper electrode and the lower electrode of the basic inspection element may be provided with a recessed portion or a protruding portion to enlarge the observation region Ur (see FIG. 21A to FIG. 24C). Alternatively, the inspection transparent electrode may be formed while in contact with the upper electrode or lower electrode of the basic inspection element (see FIG. 26A to FIG. 32). This can suppress the influence of change in the electrode structure on the antenna performance as compared with a case that the electrode structures of all the antenna units constituting the scanning antenna are changed as described above.

In a case where the basic inspection element is determined to have the alignment failure, an antenna unit (additional inspection element) which is possibly to be the alignment inspection target may be selected in advance, and the electrode structures of the basic inspection element and additional inspection element may be changed as described above to be differentiated from the electrode structures of other antenna units.

The scanning antenna according to the embodiments of the disclosure is housed in a plastic housing, for example, as necessary. It is preferable to use a material having a small dielectric constant CM that does not affect microwave transmission and/or reception in the housing. In addition, a through-hole may be provided in a portion of the housing corresponding to the transmission and/or reception region R1. Furthermore, a light blocking structure may be provided such that the liquid crystal material is not exposed to light. The light blocking structure is, for example, provided so as to block light that passes through the dielectric substrate 1 and/or 51 from the side surface of the dielectric substrate 1 of the TFT substrate 101 and/or the side surface of the dielectric substrate 51 of the slot substrate 201 and is incident upon the liquid crystal layer. A liquid crystal material having a large dielectric anisotropy Δε_(M) may be prone to photodegradation, and as such it is preferable to shield not only ultraviolet rays but also short-wavelength blue light from among visible light. By using a light-blocking tape such as a black adhesive tape, for example, the light blocking structure can be easily formed in desired locations.

INDUSTRIAL APPLICABILITY

Embodiments according to the disclosure are used in scanning antennas for satellite communication or satellite broadcasting that are mounted on mobile bodies (ships, aircraft, and automobiles, for example) or the manufacture thereof.

REFERENCE SIGNS LIST

-   1 Dielectric substrate -   2 Base insulating film -   3 Gate electrode -   4 Gate insulating layer -   5 Semiconductor layer -   6D Drain contact layer -   6S Source contact layer -   7D Drain electrode -   7S Source electrode -   7 p Source connection wiring line -   11 First insulating layer -   15 Patch electrode -   15 e Edge of patch electrode -   15 p Patch connection section -   17 Second insulating layer -   18 g, 18 s, 18 p Opening -   19 g Gate terminal upper connection section -   19 p Transfer terminal upper connection section -   19 s Source terminal upper connection section -   21 Alignment mark -   23 Protective conduction layer -   51 Dielectric substrate -   52 Third insulating layer -   54 Dielectric layer (air Layer) -   55 Slot electrode -   55L Lower layer -   55M Main layer -   55U Upper layer -   55 c Contact surface -   56 Solid portion -   56 e Edge of solid portion -   57 Slot -   58 Fourth insulating layer -   60 Upper connection section -   65 Reflective conductive plate -   68 Heater resistive film -   70 Power feed device -   71 Conductive beads -   72 Power feed pin -   73 Sealing portion -   81, 82 Slit (recessed portion) -   83 Protruding portion -   92 Inspection transparent electrode -   101, 102, 103, 104, 105 TFT substrate -   201, 203, 204 Slot substrate -   181 Stage -   183 Microscope -   185 Camera system -   187 Guide pin -   189 Probing jig -   190, 190A, 190B, 190C Maker -   401, 402 Inspection device -   1000, 1000A, 1000B, 1000C, 1000D Scanning antenna -   CH1, CH2, CH3, CH4, CH5, CH6 Contact hole -   GD Gate driver -   GL Gate bus line -   GT Gate terminal section -   SD Source driver -   SL Source bus line -   ST Source terminal section -   PT Transfer terminal section -   IT Terminal section -   LC Liquid crystal layer -   LE Lower electrode -   UE Upper electrode -   UEe Edge of upper electrode -   R1 Transmission and/or reception region -   R2 Non-transmission and/or reception region -   Rs Seal region -   U, U1, U2 Antenna unit, Antenna unit region -   Ur, Ur1, Ur2 Observation region 

The invention claimed is:
 1. A scanning antenna including a transmission and/or reception region including a plurality of antenna units arranged in the transmission and/or reception region and a non-transmission and/or reception region located in a region other than the transmission and/or reception region, the scanning antenna comprising: a thin film transistor (TFT) substrate including a first dielectric substrate, a plurality of TFTs supported by the first dielectric substrate, a plurality of gate bus lines, a plurality of source bus lines, and a plurality of patch electrodes, the plurality of TFTs and the plurality of patch electrodes being each disposed corresponding to the plurality of antenna units; a slot substrate including a second dielectric substrate and a slot electrode provided on a first main surface of the second dielectric substrate; a liquid crystal layer provided between the TFT substrate and the slot substrate; and a reflective conductive plate disposed opposing a second main surface of the second dielectric substrate, the second main surface being located on a side opposite to the first main surface, with a dielectric layer interposed between the reflective conductive plate and the second dielectric substrate, wherein the slot electrode includes a plurality of slots disposed corresponding to the plurality of patch electrodes and a solid portion not including the plurality of slots, when viewed from a normal direction of the first dielectric substrate, in each of the plurality of antenna units, a patch electrode of the plurality of patch electrodes is disposed across a slot of the plurality of slots in a first direction and overlaps the solid portion at both ends of the slot, and when viewed from the normal direction of the first dielectric substrate, in at least one antenna unit of the plurality of antenna units, at least one of a periphery of the solid portion and the patch electrode includes a recessed portion or a protruding portion.
 2. The scanning antenna according to claim 1, wherein when viewed from the normal direction of the first dielectric substrate, in the at least one antenna unit, the recessed portion or the protruding portion includes a first recessed portion provided to the periphery of the solid portion, and the first recessed portion is located on a portion of the periphery of the solid portion overlapping the patch electrode.
 3. The scanning antenna according to claim 1, wherein when viewed from the normal direction of the first dielectric substrate, in the at least one antenna unit, the recessed portion or the protruding portion includes a second recessed portion provided to the periphery of the patch electrode, and the second recessed portion is located on a portion of the periphery of the patch electrode overlapping the solid portion.
 4. The scanning antenna according to claim 3, wherein a thickness of the patch electrode is greater than or equal to 2 μm.
 5. The scanning antenna according to claim 2, wherein a thickness of the slot electrode is greater than or equal to 2 μm.
 6. The scanning antenna according to claim 1, wherein the recessed portion or the protruding portion is provided to only some antenna units of the plurality of antenna units.
 7. A scanning antenna including a transmission and/or reception region including a plurality of antenna units arranged in the transmission and/or reception region and a non-transmission and/or reception region located in a region other than the transmission and/or reception region, the scanning antenna comprising: a thin film transistor (TFT) substrate including a first dielectric substrate, a plurality of TFTs supported by the first dielectric substrate, a plurality of gate bus lines, a plurality of source bus lines, and a plurality of patch electrodes, the plurality of TFTs and the plurality of patch electrodes being each disposed corresponding to the plurality of antenna units; a slot substrate including a second dielectric substrate and a slot electrode provided on a first main surface of the second dielectric substrate; a liquid crystal layer provided between the TFT substrate and the slot substrate; and a reflective conductive plate disposed opposing a second main surface of the second dielectric substrate, the second main surface being located on a side opposite to the first main surface, with a dielectric layer interposed between the reflective conductive plate and the second dielectric substrate, wherein the slot electrode includes a plurality of slots disposed corresponding to the plurality of patch electrodes and a solid portion not including the plurality of slots, when viewed from a normal direction of the first dielectric substrate, in each of the plurality of antenna units, a patch electrode of the plurality of patch electrodes is disposed across a slot of the plurality of slots in a first direction and overlaps the solid portion at both ends of the slot, at least one antenna unit of the plurality of antenna units further includes a transparent electrode in contact with one electrode of the solid portion and the patch electrode and thinner than the one electrode, and when viewed from a normal direction of the first dielectric substrate, the transparent electrode does not overlap the one electrode and includes an alignment controlled region overlapping the other electrode with the liquid crystal layer interposed between the transparent electrode and the other electrode.
 8. The scanning antenna according to claim 7, wherein the transparent electrode has an electric resistance greater than an electric resistance of the one electrode.
 9. The scanning antenna according to claim 7, wherein the one electrode includes the solid portion, and the alignment controlled region is disposed while overlapping the patch electrode in the slot.
 10. The scanning antenna according to claim 7, wherein the one electrode includes the patch electrode.
 11. The scanning antenna according to claim 7, wherein the transparent electrode is formed of a semiconductor film common to an active layer of the plurality of TFTs. 